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TEXTBOOK

MILITARY AERONAUTICS

We miiiit hiiild iHrjfrr «ir f\rrU nnd put the fenr of Oofl in the Oormnn hpnrt hy rondiictiriff miijor HerinI
o]>eratinnii nfrninst the (Jcrmnti flrrt. I'-IkmiI hnncs, militnrv Imscs, innniifnctiirinK renters, supply
depot* nnd r«llroHd«. This illuKtrntion vUualixed the destruction of GennHn bases across the Hhlne
by Allied Air Kleet*.

TEXTBOOK

MILITARY AERONAUTICS

HENRY WOODHOUSE

Author of "Textbook of Naval Aeronautics"
member of the board of governors of aero club of america, vice-president
aerial league of america, member of national aibeal coast patrol com-
mission, chairman of committee of flying equipment cooperating
with commandant of third naval district in organizing naval
reserve forces, trustke and chairman of committee on
aeronautics national institute of efficiency, mem-
ber of the society of automotive engineers,
educational and industrial delegate,
pan-american federation, etc., etc.

NEW YORK
THE CENTURY CO.

1918

Publuhsd, May, 1918

PREFACE

One of the purposes of this book is to make
avaihible to our prospective American aviators
the educational information regarding the man-
ner in which aviators fight the enemy — informa-
tion which the enemy gets whenever Alhed avi-
ators are brought down and printed instructions
are found on them, and by daily observations of
what the Allied aviators do.

The author has found by talking to Allied
officers and from the score or so of periodicals of
the European countries engaged in this war that
all information about modus operandi and aero-
planes and devices becomes known to the enemy
almost immediately, through the capture of
aeroplanes and aviators and through observa-
tion of repetition of actions.

Another purpose of this book is to supply to
military authorities an illustrated pen picture of
the history of the evolution of military aeronau-
tics, its present status, and the direction of its
development.

The hundreds of letters received from naval
officers regarding the value to them of the
"Textbook of Naval Aeronautics" convinced
the author of the need for a similar book about
military aeronautics rather than for a book deal-
ing with the mechanics of military aircraft and
their equipment, an extensive subject that
would fill a book as large as this volume.

The following excerpts of letters from the
commanding officers of war-ships give the gen-
eral sentiment expressed in the letters received
about the "Textbook of Naval Aeronautics,"
which are close to one thousand in number.

Acknowledging the receipt of two copies of
the text-book, one for himself and one for the
ship's library, for the use of the crew, the com-
manding officer of a United States war-ship
writes :

I know they will be of inestimable value. I have
already spent, some pleasant and instructive hours in
reading a copy and must admit I knew little of the
state of the art as applied to naval aeronautics until

this time, and I am sure officers and men will be aston-
ished to know how far this science has progressed in
our service, and I am further satisfied it will awaken
keener interest in this branch of naval activity and
produce recruits for this service among our skilled
mechanicians and those daring souls to whom the rou-
tine life aboard battle-ships may become irksome.

There is as much difference between aerial
warfare in connection with army operations and
aerial warfare in connection with naval opera-
tions as there is between the operations of the
army and navy proper. The naval aviator who
has to hunt submarines, convoy troop-ships, lo-
cate submarine mines, patrol the sea-lanes, and
manoeuver his aircraft over the sea in scouting
or bomb-dropping expeditions must have a
training which is entirely different from that of
the military aviator, who locates and watches
the movements of the enemy's artillery and in-
fantry, photographs the enemy's positions, and
cooperates in attacking soldiers in the trenches
or on the march, etc.

Hence the necessity of the two books.

Supremacy in the air is the key to victory.

"Had the Allies one thousand more aero-
planes, we could have easily defeated the Ger-
mans."

This is the general expression that one hears
as the German offensive is raging. - It is an of-
ficial as well as a public expression, and every-
body scans the reports to find out what the aero-
planes are doing and whether the Allies have
sufficient aeroplanes to maintain that supremacy
in the air which is necessary to decide the war in
favor of the Allies.

With one thousand additional warplanes, the
Allies would have been able to prevent German
aviators from mapping the Allied positions; and
could have destroyed the militarj- bases, muni-
tion-dumps, gun emplacements, the railroads
upon which the troops, munitions, and supplies
were transported. In short, they could have
prevented the massing of such a huge body of

382116

PREFACE

troops as the Germans massed for this drive.

Aeroplanes are the only things that can pass
the German lines. Thev can flv over the Ger-
man lines and they can do so at night, when
neither the anti-aircraft batteries nor the Ger-
man aeroplanes can see them.

Unfortunately, the Allies did not have this
additional aerial force. To keep one thousand
well-trained aviators on the fighting fronts, em-
ploying them daily, involves about forty per
cent, replacements in aviators, and from one
hundred to two hundred per cent, replace-
ments in machines per month. In other words,
it takes six hundred aviators per month to keep
one thousand fighting continuously, operating
day and night. Xot all of these aviators are
killed or hurt. A large number just "wear
out" after a few weeks or months of intensive
service, and cannot continue. They must be
sent back to rest or to be employed in other
work.

As for machines, they are used fast and in
large numbers. The anti-craft guns are quite
accurate at heights of fifteen thousand feet; and
speeds up to one hundred and forty miles an
hour are necessary to maintain supremacy in
the air. Landing such fast machines in small
fields leads to damaging a great many.

However, when we consider the tremendous
value of each aviator, we find that the air service
is the most im|)ortant and economic branch of
the fighting forces.

The accounts show that in 1918 night opera-
tions by aeroplanes are used more extensively.

One of the despatclies summarizes some of
the activities of the aviators as follows:

In moonlight of sufficient brilliance to permit the
reading of a newspaper, bombing planes and warplanes
swarm out, carrying high explosives, far behind the
battle zone. They broaden the area of death scores of
miles, few villages escaping.

When the sun rises, the bombers, like prowling
night birds, return to their roost ; ground fighting
speeds up, and scout fleets, succeeding the bombers,
fly low over the clashing infantry, harassing enemy
columns and observing for the artillery.

One of the reports of the daytime aerial op-
erations reads as follows :

The enemy's low-flying aeroplanes were most per-
sistent in their attack on our infantry in the forward
areas. Many of these machines were attacked and
brought down by our pilots. A total of twenty-nine
hostile machines were brought down and twenty-five
others were driven down out of control. Two enemy
balloons were also destroyed. Nine of our machines
are missing.

Our machines on Saturday carried out another suc-
cessful raid on factories in Mannheim. Nearly one
and a half tons of bombs were dropped, and bursts
were seen on a soda factory, the railway, and docks.

Several fires were started, one of which was of great
size, with flames reaching to a height of 200 feet and
smoke to 5000 feet. The conflagration was visible
for a distance of thirty-five miles.

The weather Saturday again favored operations,
and our aeroplanes were constantly emj)loyed in re-
connoitering positions of troops, in photography and
bombing, and in reporting suitable targets for our
artillery. Many thousands of rounds were fired by
our pilots from low altitudes on hostile troops massed
in villages and in the open continuously throughout
the day.

More than fourteen tons of bombs were dropped on
enemy billets, on his high-velocity guns, and on rail-
road stations in the battle area.

Our bombing-aeroplanes were attacked by thirty-
two hostile machines, and a fierce fight ensued. One of
the enemy's aeroplanes was brought down in flames,
and another was downed, and fell in the center of
Mannheim. Five others were driven down out of con-
trol.

Despite this severe combat and the enemy's heavy
anti-aircraft gunfire, all our machines returned except
two. During the night ten heavy bombs were
dropped on an important railway's bridge and works
at Konz, just south of Treves, in Germany. Eight of
these bombs were clearly seen to be bursting among
the railway's works.

It is stated officially that this is only the be-
ginning of the intensive warfare that is to fol-
low, one of the great drives that are to follow
each other in quick succession hereafter. We
must, therefore, concentrate efforts on our air-
craft program and put all the manufacturing
facilities now standing virtually idle in the
United States to turn out aircraft and parts.

No time .should be lost in adopting the plan
which is to give the Allies the supremacy in the
air that is so vital, as it will decide the war in
favor of the AHies.

Henry Woodhouse.

INTRODUCTION

As President Wilson has repeatedly pointed
out, it is most important that the country be
educated to its task.

The workers for aerial preparedness have
found in the past that the principal work was to
teach the public the hnportance of aerial pre-
paredness, the tremendous possibilities for the
employment of aircraft in connection with every
branch of the army and navy,* and independ-
ently. To teach the busy military man, so
that he would recommend the expansion of the
air service to the legislator, so the legislator
would support the military man's recommenda-
tions; to teach the engineer, so that he woidd
develop better aircraft especially suited for mili-
tary purposes; and the general public, in order
to inspire j^oung men to volunteer their services
and men and women to work for the develop-
ment of our air forces.

Now that the world's strategists agree that
the present war is to be decided in the air, and
this country has been asked and has undertaken
to supply the thousands of aviators and tens of
thousands of machines needed to maintain aerial
supremacy on the side of the Allies, the great
demand is for reliable information regarding
the use of aircraft for military purposes.

Executive military officers who want to know
the exact status of military aeronautics and the
principles of aerial strategy; students learning
military aviation who want to know in detail the
various phases of aerial warfare; aeronautic en-
gineers and manufacturers who want to know
the duties of aircraft, in order to design and
make more efficient machines; and the average

patriot who wants to learn about aeronautics in
the hope of finding an opening to employ his or
her efforts to help the Government in carrying
the war to a successful conclusion, will find in
this book the publication they have been looking
for.

Another commendable point — it has many —
is the strong message which the book carries to
the American authorities and public. The au-
thor brings out once more the importance of
air power and urges full-size measures. In this
again every one will agree. It is time that we
shun half-measures. The greatest of our na-
tional sins in aeronautic matters has been over-
reliance on minimums — minimum plans, based
on minimum understanding of the military and
aeronautic situation, further weakened by mini-
mum appropriations. We have also had some
minimum men, having minimum knowledge and
experience, who did not realize, as one must do
in war-times, the possible necessity of quick ex-
pansion, the possibility of delays, due to trans-
portation of materials, labor conditions, mis-
takes, etc.,

The one national resolution that we ought to
make in dealing with aeronautics should be to
eliminate minimums of all kinds and adopt
maximums in programs, men, appropriations,
manufacturing facilities, etc. Having adopted
maximums, let us add to each, so as to have a
substantial margin of safety to insure success
under any circumstances.

Alan R. Hawley,
President Aero Club of America.

CONTENTS

Chapter I The War to be Decided in the

Air

Aerial Supremacy Must be Maintained Day and Night

Air Service the First Line of Offence and Defence —

Tlie Use of Aircraft in Connection with Military Op-
erations— Aerial Operations Independent of Land
Forces— Cooperation Between the Army and the
Navy in Conducting Major Operations

Chapter II The Warplane for Bombing

AND Torpedo Attacks 9

The New Revolutionary Weapon Which Combines
Power, Mobility, and Control, and Permits Major
Aerial Operations Against German Military Centers
and Naval Bases — Night Raids Can be Conducted
Without Difficulty — Allies Have Never Had Enough
Large Aeroplanes With Which to Conduct Major
Aerial Operations — Huge Warplanes to do at Long
Range What Huge Guns Can Only do at Short Range
— Proportion of Bombing Planes to be Increased —
Huge Warplanes and Torpedoplanes Capable of Car-
rying Tons of Explosives— Tlie Marvelous Giant Ca-
proni Warplane — French and British Bomb-dropping
Machines — The Huge Curtiss Triplane — Long-distance
Bombing Raids not New — Long-distance Allied Raids
Into Enemy Country in tlje Western Theatre of War
— Extensive Damage Can be Done by Bombs — Night
Facilitates Bombing at Close Range — Need of Silencers
to Eliminate Noise of Approach — Bombs and Bomb-
dropping Mechanism— Bomb Sights — The Scientific
Side of Bomb Dropping — Night Bombing Requires
Knowledge of Aerial Navigation by Instruments —
Night Landing Lights — Navigation Lights — The
Sperry Automatic Pilot — Turn Into the Wind to Avoid
Drift — Formation for Boml)ing Raids — Rules for For-
mation Flying — How 1,000 Warplanes Could Raid Kiel

Chapter III Dropping Bombs from Aero-
planes 31

Chapter IV Battleplanes AND Aircraft
Guns — The Dominant Factors in Main-
taining the Supremacy of the Air .
Proportions of Different Types of Armed Aeroplanes
in the Air Service — Tlie Five Fundamental Factors in
Maintaining Supremacy in the Air — Types of Aero-
planes and Their Armament — Avions de Chasse or
Combat Machines — Avions Types "Corps d'arme" —
Used for Spotting Artillery Fire, Aerial Photograph,
etc. — Pursuit, or Combat Machines — The Triplane —
A Scientific Solution of the Problem of Getting Speed
and High Factor of Safety — Triplane Safe, Even if
Wing is Shot Away — Battleplanes That Collapsed in
the Air — Loss of Factor Safety Not Compensated —
Large Aerial Destroyers — Aeroplane Guns and Can-
non— Large Aeroplane Guns — Problems of Armoring —
Vulnerable Parts of the Aeroplane — Bullets vs. High
Explosive Shells — Fast vs. Slow Muzzle Velocity — Re-
coil ; a Solved Problem — Tactics in Air Duels — ( 1 ) Air
Duels in Which Participants are Both Air Fighters
Whose Only Function is to Keep the Sky Clear of En-
emy Machines — (2) Air Duels Between Combat Ma-
chines and Armed Photographing, Spotting, or Bomb-
ing Machines — (3) Air Duels Between Large Armed
Aeroplanes — Formation in Air Fighting — Lamp Sig-
nals for Use of Leaders of Formations — Offensive
Fighting Tactics — Thorough Knowledge of Weapons is
Requir^

PAGE

Chapter V The Fundamental Principles

OF Aerial Combat 63

Chapter VI Directing Artillery Fire by

Night and Day Signaling to and from

Aircraft "^^

Methods and Codes Used for Communicating From and
to Aircraft — Tlie Observer's Special Map — Signaling
With Very's Lights — Kite Balloons for Spotting Artil-
lery Fire — The Dubilier-GoU Semi-Radio Telephone
System for Captive Balloons — Signaling Between Air-
craft— Cooperation Between Balloons and Artillery

Chapter VII Kite Balloons the Eyes of

the Artillery 81

Maneuvering — Camp Equipment of a Kite Balloon
Unit — An Artillery Captain's Experience — Personnel
of Kite Balloon Company — Preparations for Ascen-
sion— What You Can See from a Kite Balloon — Aero-
plane vs. Captive Balloon — A Leap Into Space from
a Kite Balloon — A Curious Maneuver — A Drama at the
End of a Cable

Chapter VIII Aero Photography ... 91

Tliousands of Miles of Photographic Maps — Twenty Per
Cent of Aeroplanes at the Front Used for Aerial Pho-
tography— The Aerophotographic Organization of an
Army — Seven Aeroplane Bombs Photographed Soon
After Release by the French Aviator That Released
Them on a German Plant — Aeroplane Photography
That Shows Minutest Details of a Factory Cliimney
Being Repaired — A Photographic Officer Should be Fa-
miliar With the Following Technical Subjects — Cam-
eras and Fittings — Loading of Plates — Negative Devel-
oping— Finish of Work — A Squadron Photographic
Non-commissioned Officer With His Three Men Should
be Familiar With the Following — Science of Aeropho-
tography Still Young — Essentials in Aerophotographs
— Relative Elevations Hard to Show — Interpreting
Photographs Requires Skill — Problems of Aerophotog-
raphy — Different Types of Cameras — Possible Troubles
in Taking Aero Photographs and Their Remedy

Chapter IX Reconnaissance and Contact

Patrol Work by Aeroplane .... Ill

Five Types of Reconnaissance — Procedure in Issuing
Orders "for Reconnaissance — How Reconnaissance Aero-
planes are Guarded and Protected — Protecting Recon-
naissance Machines — Navigation Rules for Reconnais-
sance— Pilots and Observers — Aircraft Report Diary
Contact Patrol (Aeroplanes De Liason)

Chapter X Night Flying 126

Zeppelin Raids Forced Aeroplane Night Flying — Long-
distance Bombing Night Raids — Aeroplanes Cannot
be Seen One Hundred Feet Away — The Operation of
Aeroplanes by Night — Lighting the Aerodromes — The
"Honig Circles" Signals for Night Flyers — Lights for
Night Landing Grounds — Returning from Night
Flights — The Signals — Lighting Equipment of Aero-
planes— Instruments Painted with Luminous Com-
pounds— Adventures in Night Flying

Chapter XI Radio for Aeroplanes

139

CONTENTS

Chaptee XII Military Aerostatics

Dirigible Balloons — Rigid, S«>mi-Ripid. and \on-Rigid
Dirigibles — Military Observation Balloons — Employed
at Nght as Well as in the Daytime — For Directing
Artillery Fire — Hydrogen Supply and the "Nurse" —
The Windlass — Free Balloon Training Necessary — The
Free Balloons — Synopsis of the Course of Training at
United States Army Balloon School

Chapter XIII Hydrogen for Military Pur-
poses

page
157

167

Proportii-s of Hydrogen — Vitriol Process — Electrolytic
Metiiod — Silicol Process — Iron Contact Process — Alu-
minum Caustic Soda Process — Hydrolithe — Hydroge
nite — Hydrogen from Water — Gas — Aluminum Potas-
sium Cyanide Process — Acetylene Process — Iron and
Water Process — Silico-Acetylene Process — Decarbura-
tion of Oils

Chapter XIV Training Aviators for the
United States Army ; Home and For-
eign Service

Schools of Military Aeronautics (Ground Schools) —
Instruction in the Junior Wing — Instruction in the
Senior Wing — Training at Army Aviation Schools —
Tests for an Aviator's Certificate — Spherical Balloon
Pilot's Certificate — Dirigible Balloon Pilot's Certifi-
cate— Aviator's Certificate — Hydroaeroplane Pilot's
Certificate — United States Army Preliminary Flying
Test — United States Army Reserve Military Aviator
Test

Chapter XV' Regulations for Uniforms of
U. S. Aeronautic Personnel

Uniform Specifications — Coats, Aviator, Anti-sinking —
Face Mask, Aviators — Flying Suit — Gloves, Aviator,
Winter — Gloves, Aviator, Summer — Goggles — Helmet,
Aviators, Summer — Helmet, Aviators, Winter — Avia-
tion Service — Mufflers — Shoes, Aviator, Winter — Boots,
Rubber, Wading (Wading Pants) — Breeches, Winter,
Motorcycles — Insignia, SU-eve — Changes in Regulations
for the Uniforms of the United States Army, 1014,
to Cover Aviation — Uniforms of the United States
Army — Officers — Enlisted Men

Chapter XVI Aeronautic Maps

Five Types of Aeronautic Maps — Tlie Map With Pho-
tographic Reproduction of Route and Information Re-
garding Prevailing Winds — The War Prevented an
International Convention on Aeronautic Cartography
— Existing Aeronautic Maps are the Result of Work
by Aero Clubs

Chapter XVII History of United States

Army Aeronautics

Aeroplanes of All Types Purchased by the Signal Corps
— The Mexican Campaign Found the United States

179

190

197

204

PAQB

Army Unprepared Aeronautically — Aircraft Board
Created— The $1,0.32,294,260 Army Air Program— Long
Delay in Extending Plans and €retting Appropria-
tions Causes Trouble

Chapter XVIII The Evolution of Mili-

tary Aviation

222

Signal Corps Specification, No. 486 — General Condi-
tions of French Military Competition of 1910-1911 —
The Kaiser's Prize for a Motor Competition — Aero-
planes First Used for Military Purposes in the Italian-
Turkish War — French Aviation Developed by Public
Interest — Firing Guns, Dropping Large Bombs, and
Two-engined Aeroplanes Once Considered Impossibil-
ities— British Army Tests for Aeroplanes in 1914 —
Aeronautics at the Outbreak of the War — Advent of
Large Warplanes in 1917 Permitted Conducting Major
Aerial Operations — The United States Lagged Behind
for Seven Years — Aero Club of America's Monumental
Work in Developing Our Aerial Forces — America's En-
try Into the War Brings Decision to Concentrate Ef-
forts to Strike Germany Tlirough tlie Air — Tlie Prob-
lem of Delivering Aeroplanes to Europe — British Air
Ministry Created

Chapter XIX Some Problems in Aero-
plane Construction

Military Functions of Aeroplanes— Some Problems in
Construction — Propeller Stresses — Suggestions for Im-
provements in Design

Chapter XX Methods of Measuring Air-
craft Performances

Aeroplane Testing — Speeds

245

259

Chapter XXI The Sperry Automatic

Pilot 269

Incorporating a Gyroscopic Reference Plane and Clin-
ometer for Aeroplanes — Its Application for Military
Purposes

Chapter XXII The Case for the Large

Aeroplane 274

Aerodynamical Bases of Comparison — The Effect of an
Increase in Size on the Structural Weight of Aero
planes — The Effect of an Increase in Siz.e Upon an
Aeroplane's Performance — Tlie Large Machine from the
Pilot's Standpoint

Chapter XXIII Every Military Aviator
Ought to Know What His Own and the
Enemy's Machine Can do and How They
Look 282

Index 293

TEXTBOOK

MILITARY AERONAUTICS

A squadron of Gotha biplanes which raided I.ondon in full daylight on July 7th, 1917. They were equipped with two 260 horse-
power Mercedes engines and carried 800 pounds of explosives. Forty people were killed and 19-1 injured.

CHAPTER I

THE WAR TO BE DECIDED IN THE AIR

This war is to be decided in favor of the side
which maintains its supremacy in the air
through having the largest number of efficient
aircraft and airmen.

The world's strategists agree on this point,
and the struggle for command of the air is rag-
ing.

The air service is the balance of power, a
most marvelous power combined with unlimited
mobility and control to such a tremendous ex-
tent that it makes of the aircraft a new arm of
revolutionary potentiality.

Aerial Supremacy Must Be Maintained
Day and Night

Command of the air means maintaining su-
premacy in the air by day and by night.

Holding supremacy of the air during the day-
time avails little if the enemy has supremacy of
the air at night, and vice versa.

Aerial supremacy at night can be main-
tained by conducting extensive night-bombing

operations against German military centers,
military supply bases, and railroads, and by sub-
stantial naval aerial operations, also at night,
against the German fleet and U-boat bases,
striking the ships of the German fleet with tor-
pedoes launched from torpedoplanes, and the
U-boats and their bases with bombs dropped
from the air.

Aerial supremacy during the daytime
means guarding the different fronts with an
overwhelming number of aeroplanes of the
fighting type, as well as with the types used for
regulating artillery fire, for aerial photography,
for scouting, and in connection with infantry
and cavalry operations; and by short, daylight,
bombing expeditions.

Major aerial operations, supported by ener-
getic military operations on land and naval
operations at sea, could, as Admiral Fiske has
pointed out repeatedly, in a comparatively brief
period of time destroy Germany's strength as
nothing else can. They could do more than
the addition of a million men on land and five

TEXTBOOK OF ^IILITARY AERONAUTICS

Caproni warplanc — one of the largest warplanes In the world.

naval squadrons at sea could accomplish: be-
cause, as is generally admitted, additional men
would avail little against the entrenched Ger-
man lines. Capturing lines at present involves
going through many lines of trenches ; and that
involves lengthy preparatory activities.

The same thing is true at sea; ships and
men can do little against the protected German
fleet, because of the miles of mines and other
defenses which guard it.

As Admiral Fiske has pointed out in the
"Textbook of Naval Aeronautics," the large
warplane combines power, mobility, and control
as no other weapon does, and permits the quick
concentration on any given point of large
jnasses of explosives.

• Aircraft can flj' over all obstructions, both at
sea and on the land, as though they did not ex-
ist. True, during daylight squadrons of Ger-
man battleplanes and hundreds of German anti-
aircraft guns would attempt to prevent the
progress of the Allies' raiding forces, which
would involve casualties, although only a frac-
tion of the casualties that result every day in the
least important land operations.

Air Service the First Line of Offense and
Defense

The air service has become the first line of of-
fen.se and defense. Every military operation is
preceded by aerial operations which include:

(1) Bombing the enemy's bases, destroyin<)-
railroads, trains, and enemy material.

This is done with bombing aeroplanes, self-
sufficient, or protected by fighting machines.
(See chapters on "Battleplanes and Aircraft
Guns" and "Warplanes for Bombing and Tor-
pedo Attacks.")

(2) Fighting hostile aeroplanes, preventing-
them from making aerial reconnaissance or tak-
ing photographs of one's positions, thus direct-
ing the fire of their artillery, etc. Small,
fighting aeroplanes are used for this purpose.
(See chapter on "Battleplanes and Aircraft
Guns.")

(3) Reconnoitering. Determining the
strength of the enemy, its composition, disposi-
tions, and probable intentions. Aeroplanes of
different types are used for this purpose.

(4) Photographing the enemy ])ositions.
These photogi-aphs, by giving accurate details
of the enemy's position, permit conducting op-
erations based on exact information, and there-
fore afl'ord the greatest chance for success.
Aeroplanes and kite-balloons are used for this
purpose.

(5) Directing artillery fire. This is done
with both aeroplanes and kite-balloons, and has
become an exact science.

(6) Contact patrol. Coordinating the ac-,
tivities of the different arms during attacks. Tn|
this role the aviator becomes the master-mind
that watches over everv movement of the eneiiiv.

THE WAR TO BE DECIDED IN THE AIR

as well as of his own forces, and transmits to his
own forces information regarding the advance,
retreat, and other movements of the enemy, di-
recting the sending of reinforcements to the
weak or threatened points, and controlling the
fire of the machine-gun batteries as well as of
the artillery. Aeroplanes of different types
are used for this purpose.

(7) Cooperating with the infantry and other
arms in taking trenches, by flj'ing low over the
trenches and attacking the enemy with machine-
guns. Different types of one- or two-passen-
ger aeroplanes are used.

(8) Cooperating with the artillery and other
arms by attacking the crews of hostile batteries
with machine-guns. Different types of one- or
two-passenger aeroplanes are used for this pur-
pose.

(9) Making attacks with bombs or gims
against land forces, to engage the enemy and
distract his attention from ope^-ations which are
about to be conducted ; in other words, perform-

ing the functions of cavalry, which has been
used but httle along the western front.

(10) Conducting aerial attacks from the
rear with bombs and machine-guns against
enemy land-forces, to relieve the pressure being
brought by the enemy's forces against any one
point, or to wear down the strength of the ene-
my's land-forces. Different types of battle-
planes are used for this purpose.

(11) Preventing reinforcements from reach-
ing the enemy, by flying far into the enemy
lines, watching for trains and attacking them
with bombs and machine-guns. Different
types of battleplanes are used for this purpose.

The Use of Aircraft in Connection with
Military Operations

The use of aircraft in connection with mili-
tary operations has become so extensive that it
may be said that the air service, cooperating
with the land-forces, is, in itself, an aerial army,

A remarkable pliotojiraph of the capture of German trenrhes by the French infantry on the Somme. This photograph was taken
by a French aviator at a height of only 500 feet. The trench in the left foreground, named the Guillaume Trench, had formed the
German front line. Slanting up to it from the right-hand corner is a communication-trench, by which French reinforcements are seen
arriving. Shell craters are seen everywhere.

TEXTBOOK OF MILITARY AERONAUTICS

Air craft can go over all obstructions which stop the pnif^rc^s of .snii)s and armies. How conipktc is its supremacy may be seen
from the above photograph, taken from an Italian military aeroplane (part of which is shown in the photograph) while crossing
the Alps. Italian aviators connected with the Trentin Army flew daily under such conditions.

the aeroplanes performing the function of cav-
alry, artillery, and infantry.

General Haig, commander-in-chief of the
British forces in France, in his official reports
has stated repeatedly that the employment of
aeroplanes in connection with military opera-
tions is practically unlimited.

In one of his latest reports he speaks of the
work of the Royal Flying Corps as follows :

"In this combination between infantry and
artillery the Royal Flying Corps jAayed a
highly important part. The admirable work
of this Corps has been a very satisfactory fea-
ture of the battle. Under the conditions of
modern war the duties of the Air Service are
many and varied. They include the rcgu'ation
and control of artillery fire by indicating targets
and observing and reporting the results of
rounds; the taking of photographs of enemy
trenches, strong points, battery positions, and
the effect of bombardments; and the observa-
tion of the movements of the enemy beliind his
lines.

"The greatett ikUl and daring has been
ihown in the performance of all these duties, as

well as in bombing expeditions. Our Air Serv-
ice has also cooperated with our infantry in their
assaults, signaling the position of our attacking
troops and turning machine-guns on the enemy
infantry and even on his batteries in action.

"Not only has the work of the Royal Flying
Corps to be carried out in all weathers and
under constant fire from the ground, but fight-
ing in the air has now become a normal pro-
cedure, in order to maintain the mastery over
the enemy's Air Service. In these flights the
greatest skill and determination have been
shown, and great success has attended the ef-
forts of the Royal Flying Corps. I desire to
point out, however, that the maintenance of
7nastery in the air, xchich is essential, entails a
constant and libera! supply of the most up-to-
date machines, without which even the most
skilful pilots cannot succeed.

"The style of warfare in which we have been
engaged offered no .scope for cavalry action,
with the exception of the one instance already
mentioned, in which a small body of cavalry
gave useful assistance in the advance on High
Wood."

THE WAR TO BE DECIDED IN THE AIR

Aerial Operations Independent of
Land-Forces

Aerial operations independent of the land-
forces are increasing in number and extent.
The advent of large battleplanes with a flying
radius of close to 1000 miles, and capable of
carrying one ton or more of explosives, will in-
crease the extent of bombing operations.

It is, roughly, between 450 and 500 miles
from Great Britain to Kiel, Wilhelmshaven,
and Helgoland. It is less than 300 miles from
the Allies' lines to Essen and Diisseldorf, and
it is less than 100 miles from the main Allied
aeronautic bases to Zeebrugge and Ostend,
which are important bases for U-boats and
German destroyers.

Details regarding the types of warplanes
used for bombing and major operations are
given in the chapter on "The Warplane for
Bombing and Torpedo Attacks."

Cooperation Between the Army and the

Navy in Conducting Major

Operations

As pointed out in the "Textbook of Naval
Aeronautics," it is difficult to define the lines of
demarcation where the navy ceases to operate

and the army begins to operate, and vice versa.
The Allies have, very wisely, combined their
aerial resources to conduct major aerial opera-
tions.

It would be hard to figure out under whose
jurisdiction a raid should be conducted which
involves flying over land and sea; therefore all
lines of demarcation have been wiped out in so
far as major operations are concerned, the
bombing squadrons usually including army and
naval aviators of two or three of the allied na-
tions. It is to be expected, therefore, that
army aviators will be called upon to participate
in operations in which their aeroplanes will
carry torpedoes, to be used in attacks against
the German fleet, just as naval aviators have
been called upon to conduct bombing operations
against German military bases, as in the case of
the raids on Essen and Obendorf .

In the United States the army has charge of
the coast defense ; therefore the army air service
uses land and water aeroplanes, airships, and
captive balloons.

The functions of aircraft for coast defense
are:

( 1 ) For reconnaissance, patrolling the coasts,
looking for hostile ships of all types, enemy sub-

A French Nieuport fighting aeroplane photographed as it was passing another military aeroplane in midair.

TEXTBOOK OF MILITARY AERONAUTICS

marine bases, and mines. Aeroplanes, large
and small, land and water, and dirigibles are
used.

(2) To prevent the landing of enemy forces
by attacking the hostile ships and transports
with torpedoes, guns of large caliber, and
bombs. Aeroplanes, land and water, and dirig-
ibles are used.

(3) To attack hostile bombarding and block-
ading ships with torpedoes, guns, and bombs.
Aeroplanes, land and water, and dirigibles are
used.

(4) To direct and spot the fire of coast de-
fense batteries. Aeroplanes, land and water,
dirigibles, and captive balloons are used.

(5) To fight off enemy aircraft, preventing

them from gathering and transmitting informa-
tion about the location and disposition of our
coast defenses. Aeroplanes and dirigibles are
used.

(6) To transmit confidential information be- .
tween militarj' stations. Aeroplanes and dirig-
ibles are used.

(7) To convoy troopships, merchantships and
army transports on coastwise trips. Aero-
planes, land and water, and dirigibles are used.

(8) To locate mine-fields and assist trawlers
in destroying mines. Aeroplanes, dirigibles,
and captive balloons are used.

(9) To serve as the "eyes" in planting mines.
Captive balloons, dirigibles, and aeroplanes are
used.

The effect of a bomb dropped on an aeiodioiiie at ftaionica by a Cjeniian aeroplane. It just missed hitting the hangars and garage.

CHAPTER II

THE WARPLANE FOR BOMBING AND TORPEDO ATTACKS

The New Revolutionary Weapon Which Combines Power, Mobility, and Control, and
Permits Major Aerial Operations Against German Military Centers and Naval Bases

It is generally agreed that the most effective
and quickest way of achieving victories of de-
cisive importance over Germany is :

( 1 ) By conducting substantial bombing oper-
ations against German military centers, military
supply bases, and railroads;

(2) By conducting substantial aerial opera-
tions against the German fleet and U-boat bases,
striking the Gei-man fleet with torpedoes
launched from torpedoplanes and the U-boats
and the bases with bombs dropped from the air,
as well as with shots from aeroplane guns of
large caliber.

Such major aerial operations, supported by
energetic military operations on land, and naval
operations at sea, could, as Admiral Fiske has
pointed out repeatedly, in a comparatively brief
period of time destroy Germany's strength as
nothing else can. They could do more than
the addition of a million men on land and five
naval squadrons at sea, because, as it is gener-

ally admitted, additional men could do but lit-
tle against the entrenched German lines. Cap-
turing lines at present involves going through
many lines of trenches, and that involves
lengthy preparatory^ activities.

The same thing is true at sea; ships and men
can do but little against the entrenched German
fleet, because of the miles of mines and other
defenses which protect the German fleet.

As Admiral Fiske has pointed out in the
"Textbook of Naval Aeronautics," the large
warplane combines power, mobility and control
as no other weapon does, and permits the quick
concentration on any given point of large
masses of explosives.

Aircraft can fly over all obstructions, both in
the sea and on the land, as though they did not
exist. Tnie, during daylight, squadrons of
German battleplanes and hundreds of German
anti-aircraft gims would attempt to prevent the
progress of the Allies' raiding forces, which

TEXTBOOK OF MILITARY AERONAUTICS

would involve casualties — although only a frac-
tion of the casualties that result every day in
the least important land operations.

Night Raids Can Be Conducted Without
Difficulty

A thousand aeroplanes could flj' from the
nearest Allied bases to the German bases at
Kiel and Wilhehnshaven, or to Essen, Berlin,
and other German military centers, almost un-
seen.

At night aeroplanes can hardly be seen a hun-
dred feet away by other aeroplanes, and it is a
most difficult thing for searchlights to locate
them in the sky. Under the best weather con-
ditions and a fairly clear night, a squadron of
Allied aeroplanes started from Salonica re-
cently to bomb the German lines. They ar-
rived over the German lines, and were surprised
when all at once the lights of the German aero-
drome were lighted. The Allied aviators
dropped their bombs and returned to their own
aerodrome — to find that German aviators had
in the meantime bombed the Allied lines. The
squadrons had passed each other en route, but
neither side had sighted the other. In each
case the officers in charge of the aerodromes
lighted the aerodromes when they heard the
noise of motors, thinking that their aviators
were returning from their bombing raid. In
scores of cases single aeroplanes or fleets of five

or more aeroplanes have carried on bombing
raids during the night without being seen by
Germans. Therefore, the solution of striking
Germany through the air rests in night raids.

Allies Have Never Had Enough Large

Aeroplanes with Which to Conduct

Major Aerial Operations

Neither the Allies nor the Teutons have had
a sufficient number of large aeroplanes to per-
mit them to conduct major aerial operations
against the other side. While there are now
thousands of aeroplanes employed, whereas
there were only a few hundred in the beginning
of the war, the use of aeroplanes has been so
greatly extended, and they are used for so many
miportant purposes in connection with military,
coast patrol, and naval operations, that it has
been impossible to accumulate the number of
aeroplanes recjuired for major aerial operations.

It is also true that until recently there were
not available the types of large aeroplanes re-
quired for long distance bombing or torpedo
launching operations.

Huge Warplanes to Do at Long Range What
Huge Guns Can Only Do at Short Range

Major R. Perfetti, the head of the Special
Italian Commission for Aeronautics in the
United States, brought to the attention of the

Tlie Gcriiinii Gotliii warpliinc.

THE WARPLANE FOR B03IBIXG AND TORPEDO ATTACKS

When the "Emergency Air Fleet" Crosses the Rhine!

Allied military authorities the fact that huge
warplanes can do at long range what huge guns
can only do at short range. He pointed out
that, just as reducing the fortresses and posi-
tions which were supposed to be invulnerable
was done by concentration of the fire of many
huge guns, the reducing of distant military and
naval bases can be accomplished by the drop-
ping of tons of explosives simultaneously by
hundreds of warplanes.

This was an obvious truth, which heretofore
could only be figured out theoretically, but not
proven in practice, because of the lack of war-
planes powerful enough to carry tons of explo-
sives. jSIajor Perfetti could state it as a tested
and proven truth, because Italy has the huge
warplanes needed for these operations, and has

been using them on a limited scale in her oper-
ations against the Austrians over the moun-
tains and across the Adriatic Sea.

If the United States takes steps promptly to
build thousands of these huge triplanes, it is
possible that substantial deliveries will begin to
be made in six months, making it possible to
figure on aerial operations against the German
naval and military bases next spring and sum-
mer. Nothing else affords such possibilities.

Proportion of Bombing Planes to Be
Increased

Heretofore, owing to limited production, the
proportion of bombing planes to the number of
aeroplanes used has been only about ten per
cent. Twenty per cent, have been small, fast

TEXTBOOK OF MILITARY AERONAUTICS

A British aviator throwing a bomb.

fighting machines to fight enemy aviators en-
gaged in similar work, or in photographing, di-
recting artillery fire, reconnoitering, etc.

Now that the United States has entered the
war, and has mobilized manufacturing resources
to the point where a program to munufacture
100,000 aeroplanes could be completed in three
years, the proportion of bombing planes can be
increased by the addition of thousands of huge
bombing warplanes, many of which can be man-
ufactured in America, the Italian Government,
like the British and French Governments, hav-
ing offered to cooperate with the United States
Government.

Huge Warplanes and Torpedoplanes Cap-
able of Carrying Tons of Explosives

The Allies now have huge warplanes and tor-
pedoplanes capable of carrying from two to
three tons of explosives or torpedoes. The

gigantic Caproni torpedoplanes permit aerial
o])erations from any of the Allied bases to any
German naval or military base and return —
with substantial reserve fuel.

The Curtiss triplane air-cruiser, while handi-
capped by the heavy flying-boat hull, is also a
good possibility. The twin-motored Handley-
Page biplane and the new three-motored Gal-
laudet seaplane are among other possibilities
for long-distance aerial raids.

The Marvelous Giant Caproni Warplane

Italy leads in types of bombing and gun-car-
rying aeroplanes.

The following are some of the most important
types of Italian aeroplanes, types which, if
built by thousands, will make it possible for the
Allies to conduct the major aerial operation
a'?ainst Germany which is to ensure her down-
fall:

(1) The largest Caproni triplane. This re-
markable warplane is equipped with three large
h.p. Fiat motors. The details about this ma-
chine are kept secret, but it is known that the
machine, as a whole, follows the characteristics
of the Caproni warplanes. This machine,
judged by the smaller types, must carry about
five tons of explosives and fuel for twelve hours,
at a speed of about eighty miles an hour.

(2) The small bombing type Caproni tri-
plane. This machine, which is illustrated here-
with, is a triplane, with two fuselages, equipped
with three Fiat or Isotta-Fraschini motors, two
in front fitted with one propeller respectively,
and one in the rear, also fitted with one pro-
peller. Each of the engines is independent of

Italian Battleplane.. From left to rl.ht: th- C.pronl triplane. .•,uipp,-.l v.i.1. .h"-^ •-.> '<

tors.

THE WARPLANE FOR BOMBING AND TORPEDO ATTACKS

The Italian Caproni warplane returning from a flight.

the others, so that if two of the engines should
stop, the machine could still keep in the air with
the power of one motor.

(3) The bombing type Caproni biplane.
This type of machine is most remarkable for
its speed. It is equipped with three Fiat or
Isotta-Fraschini motors of 200 h.p., and three
propellers, two tractors and one pusher.

French and British Bomb -Dropping
Machines

The following are a few of the many French
and British bomb-dropping, gun-carrying ma-
chines:

The British Handley Page, equipped with
two Rolls-Royce motors. This biplane has

carried 21 passengers in one flight and has a
top wing-spread of 98 ft. and a lower wing of
98 ft. It has mountings for large guns.

The twin-motored Avro biplane, a triplace
equipped with various kinds of motors.

In the "short distance" class of bombers are:
The Sopwith 130 h.p. triplane known as the
"Tripe Hound." This is a single seater
equipped with a Clerget motor.

The two seater 1Y2 strut Sopwith biplane
equipped with a Clerget motor. This is used
extensively by the Royal Naval Air Service for
bombing, and the Royal Flying Corps for
fighting.

To these must be added the machines de-
signed by the Royal Aircraft ISIanufactory,
which include the BE-2C, R. A. F. motor, rather

Caproni biplane: the small Italian fifljhting Monoplane, and the Caproni bombing biplane.

TEXTBOOK OF MILITARY AERONAUTICS

POSITION OF SIGHT
when bomhs arc rcleasi-d on lo
2nd Tari(ct

The l*f>in!cr (sec dUij(rani inset)
was first set at 12 dc4rcc\ ; then
vktial ray aJvjnccd to 2nd
'1 .irSct hy tiltinjt prisni, the
'.:i4i.-l bcinit held in sntht by
^: .iiJually reducing anfilc until
lidt-^rtts rtachcd, when pointer
:iiiil bi^nihs arc rcIcawJ

Dmawixo muM THE Ix>MtK>N Okai*i(u SiiowiNti IIow Tiir (itmiA AiMH Its Homiim

Thr art of arrlal iMmibardmrnt \h liirjrrly n ?imttrr of lurk. To n'tliirr this i-Innrnt thr rnrmy bus pnKlutvd the instruinciit lllus-
tratrd, thr Grorz boinlwIroppcr'H trloM-opic hijrht, which Is included In the equipment of the Uotha, wliich lias u speed of ninct/-
thrrc miles an hour, therefore make« accurate hitting dlfHcult.

THE WARPLANE FOR BOMBING AND TORPEDO ATTACKS

British airmen taking the offensive against a German brigade concentrating for .ittnck near Arras. The aviators discovered
the Germans concentrating for an attack and dropped heavy bombs on them, destroying their machine guns and ammunition and
dispersing them. In addition, the aviators advised the British artillery which opened fire on the German concentration, so that the
German attack was never even launched. — (Drawing by the "Illustrated London News'" artist.)

slow and a poor climber, but a good machine for
night flying, on account of its inherent stabil-
ity; the BE-2E, the FE, which is a two-seater
pusher fighting machine ; which is a faster scout,
just being tested, and the BE-12. Also the two-
passenger Avro, armed with one or two guns.

The French also use a great many different
types of machines, the following being used for
bomb-dropping:

The Breguetj equipped with a single motor.

The Caudron G-4, pilot and observer;
equipped with two La Rhone motors.

The Caudron R-4, three-passenger.

The Farman, pusher type, two-passenger,
equipped with one Renault motor.

The Germans have several tj^pes of bombing
machines, of which the Gotha is most prom-
inent. It is a biplane equipped with two 260
h.p. jVIercedes motors, carries fourteen bombs,
and is armed with three guns.

The Huge Curtiss Triplane

The huge Curtiss triplane air-cruiser built

for the British Government is a good possibility

The Caudron G-6, two-passenger; equipped as a long-distance bomb carrier, for aerial oper-

with two La Rhone motors. ations against Germany. For such a purpose

The Dorand A-R, two-passenger; equipped the boat-hull can be eliminated, and its weight-

with one motor. carrying ability increased thereby. Having

The Farman, pusher type, two-passenger; multiple power-plants, it can make the flight

equipped with 170 h.p. Renault motor, carry- from an Allied base to Kiel or Berlin or Essen

ing one or two Lewis guns forward.

The Letort, equij^ped with two motors.

The Moineau, three-passenger; one motor,
connected to drive two propellers.

The Voisin-Peugeot, two-passenger ; equipped
with a Peugeot motor.

with a good margin of flying ability.

The big Curtiss triplane, with a few changes
in construction, will make a most efficient tor-
pedoplane, capable of carrying a magazine of
torpedoes.

The new three-motored Gallaudet seaplane

TEXTBOOK OF MILITARY AERONAUTICS

The Twin-Motored Handlcv Pajrc Bomhinfr Biplane. A Handley Pape has flown from London to Asia Minor, with stops, and
dropped bombs on Constantinople. It carried seven men, spare motors and supplies. Larger Handley Pages can fly across the
Atlantic and bomb the German bases and munition plants.

The Krrnrh Farmnn mnrhinc rquip|>r<l with a Dietrich motor, used cxtrniilvrly for Immbing.

THE WARPLANE FOR BOMBING AND TORPEDO ATTACKS

also comes in the class of long-distance raiding
machines and is suitable for either bomb-drop-
ping or torpedo-launching. A number of
other large machines are under contemplation
or are being designed by different American
manufacturers, but the details are not yet avail-
able.

Long-Distance Bombing Raids Not New

Long-distance bombing raids are by no means
a novelty, but they have always been conducted
with only a few aeroplanes of limited carrying
capacity, which carried only a few hundred
pounds of bombs besides the fuel needed for the
journey.

Among the historic bombing raids, for sev-
eral reasons, is the raid on Karlsruhe, on June
15, 1915. It was conducted by twenty-three
twin-motored Caudron machines in charge of
Captain de Kerillis, and dropped close to 50
large bombs on Karlsruhe. Three of the ma-
chines did not return ; they had to land and were
captured, but the damage to Karlsruhe was
serious.

In the very first bombardment of Sofia, on
April 21, 1916, a single aviator started from
Salonica, flew to Sofia, dropped four bombs and
proclamations announcing the capture of Trebi-
zon, and returned to Salonica. This exploit
was repeated by single aviators from time to
time; then on September 15, 1916, it was re-
peated by four aviators who left Salonica at
6:20 and arrived over Sofia at 8:40. They
dropped their bombs, many of which were effec-
tive, and returned. They had crossed the Bal-
kan iSIountains at 6000 feet without trouble and
had accomplished what an army could not have
done. The only limitation was that the aero-
planes were too few in number to win a decisive
victory. In every raid in the Balkans only four
or five aeroplanes participated.

Among the most remarkable long-distance
bombing raids were the raids on Essen and
Munich by Captain de Beauchamp and Lieu-
tenant Daucourt, on September 24 and Novem-
ber 18, 1916, which have been repeated since by
other aviators. The raid on Ludwigshafen, ac-
complished on May 27, 1915, in which 18 aero-
planes took part, also involved a flight of about

Plotting a Bombing Raid.

TEXTBOOK OF MILITARY AERONAUTICS

|- 1^/ )

\^-^/T- 1 1 1,' ffi — ^J?^^

K^-^ / ^

■7

KIEL

Plan of Kiel and Kiel Canal from Count de Beaufort's hook,
"Behind the German Veil." The author points out that Kiel
is derived from the Anglo-Saxon "Kille," meaning "a safe place
for ships." The torpedoplane will make it unsafe for ships to
be there.

400 miles. It was conducted successfully, and
only one aeroplane was forced to land and was
captured. Another classic flight was the bomb-
ing raid on the Mauser Works at Oberndorf, on
Octol)er 12, 1916, in which a French bombing
squadron and a British bombing squadron par-
ticipated, escorted by the Lafayette Flying
Corps fighters. These are only a few of scores
of such raids. In all the.se raids the aviators
had to fly from five to seven hours continuously

under most trying conditions, having to protect
themselves with insufficient arms. A night raid
in large, well-armed warplanes would be easy
in comparison — and much safer.

Long-Distance Allied Raids into Enemy
Country in the Western Theater of War

The following list of the most important
French and British raids in 1916, together with
twenty-five important Italian raids, compiled
by London "Aeronautics," is reproduced here-
with for reference purposes:

March 20 — ^Fifty British, French, and Belgian aeroplanes attack

Zeebrugge and Houltade.
Mahch 25 — Naval raid on airship sheds in Schleswig-Holstein.
April 3 — Reprisal raid by 31 Allied aircraft on enemy canton-
ments of Keyem, Essen, Terrest, and Houthulst.
April 23 — Naval air raid on Mariakerke.
Apkil 24 — Anglo-Belgian raid on Mariakerke.
June 21-22 — French drop 18 bombs on Treves.
June 32 — Nine French aeroplanes bomb Karlsruhe, and ten bom-
bard Miilheim (Rhine) as a reprisal for the bombardment of

Bar-le-Duc and Luneville.
July 13 — French aeroplane carries out night raid on Mulheim as a

reprisal for the bombardment of Luneville.
July 19-20 — French aeroplanes bombard military establishments

of Lorrach (Baden).
July 22 — Twelve French aeroplanes bombard the military estab-
lishments of Miilheim.
July 30 — Naval raid in conjunction with the French on benzine

stores and barracks at Miilheim (.\lsace).
August 2 — Naval air raid on St. Denis Westrem and Mierelbeke.
August 8 — Fir-t night raid by Adjutants Baron and Em-

manuelli on powder factory at Rottweil, on the Neckar.
August 9 — Naval attack on airship shed at Evi-re.
August 18 — Naval aeroplanes bomb enemy ammunition dumps

at Lichtervelde.
August 25 — Naval aeroplanes attack airship sheds near Namur.
Septe.mber 2 — Naval aeroplanes bomb shipbuilding yards at Ho-

boken, near Antwerp.
September 3 — Large squadron of naval machines bombard enemy

aerodrome at Ghistelles.
SEPTf:MBER 7 — Attack on enemy aerodrome at St. Denis Westrem

carried out by naval aeroplanes.
September 9— Naval aeroplanes attack Ghistelles and Handzaeme

aerodromes and also the ammunition dump at Lichtervelde.
September 9-10 — Second night raid by Adjutants Baron -ind

Emmanuelli on powder factorj- at Rottweil.
September 11—15 — French squadrons bombard by night works

at Rombach and Dillingen.
September 1.5 — Naval aeroplanes bombard batteries at Ostend.
SEPTt:MBER 17 — Further naval raid on St. Denis Westrem aero-
drome.
Septejiber 22 — Enemy aerodrome at St. Denis Westrem again

boml>ed by naval aeroplanes.
September 23 — .\djutant Baron bombards by night military

establishments at Ludwigshafen, and continuing his route,

bombs Mannheim.
.September 2+ — Captain de Beauchnmp and Lieutenant Oauoourt

bomb the factories of Essen (Westphalia).
September 24-25 — French bombarding squadrons effect by night

an attack on the blast furnaces of Dillingen (Rhineland)

and .Saarlnuis.
.September 27— Naval raid on airship shed.s at Ev^re. Berchem

St. Agathe. and Ettcrbeik.
October 5 — French bombard aviation ground at Colmar (.\1-

sace).

THE WARPLANE FOR BOMBING AND TORPEDO ATTACKS

Night raid by French aeroplanes on electric searchlights and
buildings at Zeebrugge.

October 9-10 — Adjutants Baron and Chazard bombard by night
the Bosch magneto factory at Stuttgart.

October 10-11 — French night raid on Lorrach establishment,
Colmar aviation ground, and Mulheim railway station.

October 13— Franco-British squadron of 40 aeroplanes bom-
bard the Mauser works at Oberndorf.

October 32 — French aeroplanes bombard blast furnaces of
Ilagondange.

October 23— British aeroplanes carry out a further attack on
Hagondange.

November 9 — French aviator bombs railway station of Ofen-
burg.

November 10 — Xaval raid on Zeebrugge Ostend.

Seventeen British aeroplanes bombard the steel works of
Frocklingen (northwest of Sarrebruck) and other factories
in the Sarr region.

November 10-11 — Further night attack by French aeroplanes on
same factories.

November 12 — A squadron of naval aeroplanes carry out an at-
tack on Ostend harbor.

November 15— Further naval attack on harbor and submarine
shelters at Ostend and Zeebrugge.

November 17 — Successful raid on Ostend and Zeebrugge by naval
aeroplanes.
Captain de Beauchanip bombs Munich as a reprisal for the
bombardments of Amiens.

November 22 — Xaval aviators drop bombs on torpedo craft and
seaplane sheds at Zeel)rugge.

November 23-24 — French aviators again bombard Volklingen
blast furnaces.

November 24— British naval aeroplanes bombard the blast fur-
naces of Dillingen.

November 28 — Xaval aeroplanes carry out an attack on Zee-
brugge harbor.

December 27— Thirteen machines of the R.X.A.S. bombard blast
furnaces at Dillingen.
French dirigible l)ombards factories at Hagondange and iron-
works at X'eunkirchen.

Septe.mber 26 — Russian aviators again attack German air-sta-
tion on Lake Angern.

December 13 — Successful Russian air-raid on Tarnopol-Zloczow
rallwav.

Italian Theater

Januaby 14 — Italian air squadron bombards Aisovizza aero-
drome.

Jaxuahy IT^Italian aviator bombs Austrian headquarters at
Volano.

February 12 — Austrian seaplanes raid on Ravenna.

February 18 — Italian machines carry out reprisal raid on Laibach.

April 3 — Italian aeroplanes bomb railway at Adelsberg.

Apkil 17 — Franco-Italian raid on Trieste.

April 20 — Italian air-raid on Trieste.

May 3 — Italian airship falls into ,\ustrian hands.

May 7 — Italian air-raid over the Adige Valley.

Juxe 3 — ^Italian squadrons bomb encampments in the Astico val-
ley.

June 12 — Italian seaplanes bomb Trieste.

June 16 — Italian squadron of thirty-seven machines bomb en-
campments in the N'os Valley.

August 1 — Italian squadrons bombard the Whitehead Torpedo
and Submarine Works at Flume.

August 2 — Italian aviators bomb Durazzo.

August 15 — Italian X''leuport chasers bomb Austrian encamp-
ments near Gorizia.

August 16 — Italian aviators bomb railway at Relnenberg.

August 25 — Italian air-squadron bombs railway-station at San
Cristoforo.

September 13 — Italian machines bomb Trieste.

Septe.mber 15 — Italian squadrons bomb Comignano.

Septe.mber 17 — Italian squadrons bomb station at Dottogliano
and Scoppo.

October 31 — Italian squadrons successfully bomb Trieste rail-
way.

X'ovember 1 — Italian X^ieuport-Caproni squadron bombs enemy
camps in the Vippacco Valley.

November 7 — Franco-Italian aircraft carry out raid on the Istrian
coast.

Xovember 14-15 — Italian aviators attack airsheds at Prosecco
and the pier at Trieste.

December 30 — Italian raid on Volano and RIfemberga.

December 3 — Italian aviators attack Dottogliano and Scoppo
railway stations.

Southeastern Theater

January 23— Thirty-two French aeroplanes bomb Ghevgeli and
Monastir.

One of the three Sperry bomb sights.
The Sperrys, after gaining world-wide
fame in making scientific instruments for
ships, undertook to solve the most difficult
problems in aerial navigation and aerial
warfare. Having begun in the early days
of aeronautics they were able, through
their long experience in aeronautics, and
thorough knowledge of the problems, to
evolve some most efficient instruments.

TEXTBOOK OF MILITARY AERONAUTICS

Jakuasy 28 — Fourteen French aeroplanes bomb Bulgar camp

northwest of Lake Doiran.
May ^4 — Allied raid on Ghevgeli.
July 3 — Allied aeroplane droi)s bombs on Sofia.
AuocsT 18 — Nineteen Allied aeroplanes attack Monastir.
August 23 — Russian seaplanes bombard Varna.
August ^5-31 — Naval air raids behind Kavala.
August ^8 — French aviators destroy aviation park at Mrzenci.
August -29 — English aeroplanes bomb Drama.
September -2 — Raid on Constanza.
September 9 — Rumanian aviators bomb Rustchuk.
September 13-2^ — Naval seaplanes bomb Bulgarian coasts.
September 14 — French aviators bomb Sofia.
SEPTE.MBER 18 — English aviators drop bombs on Prosenik.
September 26 — The R.N..\.S. bomb Angista.
October 11 — French aviators bomb Prilep.
October 15 — R.N..\.S. bomb the Buk bridge.
October -23 — Naval aeroplanes bomb Buk and Drama.
October 26-2'i — English aviators reach Bucharest.
October -29 — News of the evacuation of Constanza carried to

Odessa by seaplane.
October 31 — Naval aircraft bomb railway bridge at Simsirli.
No\'E.MBER 3 — English aviators bomb Bursuk.
No\'ember 11 — Naval aircraft bomb Seres-Drama railway.

Bombs dropped on Campulung.
November 18 — British squadrons bombard Karjani, Pravishta,

and Senultos.
Xo\-ember 22 — French aeroplanes bomb enemy encampments in

tlie Topolchani and Prilep regions.
November J3-J9 — Naval squadrons bomb Bulgarian coast.
November 29 — British naval aeroplanes effect great damage at

Gereviz.
December I — Russian air raid near Constanza.
December 14 — Naval air squadron bombs Kuleli-Burgas bridge,

on the railway to Constantinople. '

The Levant

February 20 — English aviator destroys enemy's power station at

El He.ssana.
April 12 — English bomb Smyrna.

April 14 — British naval aeroplanes bomb Constantinople.
May 18 — English machines bombard El Arish.
May 25 — The R.F.C. bomb advanced posts in Sinai Desert.
May 29 — English drop more bombs on Smyrna.

June 13— The U.F.C. bomb El Arish.

August 25-29 — English aviators cany out many raids in Pales-
tine.

September 4 — R.F.C. bomb Mazar.

September 5 — English aviators bomb Turkish aerodrome at El
Arish.

October 1— English bombs dropped on Kut-el-Amara.

Octobek 10 — U.F.C. bombs Tigris camp.

Novembeb 1 — Russian aviators carry out successful raid on the
Euphrates.

Nove.mbeh 11 — English aviators carry out two successful raids
on Maghdaba and Birsaba.

Xove.mber 15 — English aviators bomb Turkish base near Sinai.

December 4 — English aviators carry out reprisal on Turkish
camps.

December 14-15 — British aviators attack Tigris pontoon bridges
by night.

Aeroplane Raids on England, 1916

Casualties

Date District Killed Injured

Jax. 23 East Coast of Kent 1 6

Feb. 20 East and Soutlieast Coasts — Lowes-
toft and Walmer 3 "h

■ Mae. 1 Southeast Coast 1 —

19 East Kent — Dover and Ramsgate 9 31

April 24 Dover — —

May 3 Deal ,. — 1

20 East Coast of Kent 1 2

Aug. 12 Dover — • 7

Oct. 22 Sheerness — —

23 Margate — 3

Total 15 59

Nov. 28 London — 9

Extensive Damage Can Be Done by Bombs

The damage that can be done by bombs is
extensive, particularly in thickly settled places.
In fast raids, whole factories and magazines

Incendiary bombs
dropped on English
soli by Zeppelins, some
bum<-<l out and some
still active.

THE WARPLANE FOR BOMBING AND TORPEDO ATTACKS

The French Briguet
Michelin warplane,

equipped with one 220
horse-power Peugeot
motor. This machine is
used extensively for
bombing.

have been blown up, railroad stations wiped out,
bridges wrecked, hangars and dirigibles de-
stroyed, ships destroyed in their docks, and mili-
tary camps and billets destroyed.

The damage has been considerable, even when
only a few aeroplanes were employed. The
emjiloyment of hundreds of aeroplanes would
■wreck entire militaiy and naval bases. A fleet
of hundreds of torpedoplanes, cooperating with
bomb-dropping planes, could attack the Ger-
man fleet at its base from every side, as well as
from above, and inflict tremendous damage, if
not destroy it completely. It depends entirely
upon the number of aeroplanes employed, and
whereas a fleet of hundreds of torpedoplanes
and bombing aeroplanes would cost far less than
a naval squadron, and could be built and oper-
ated much quicker — it could strike at the Ger-
man fleet, whereas a naval squadron could not
— it is evident that aeronautics affords the quick-
est and most effective way to strike the German
fleet, the U-boat bases, and the German military
centers. It is the opinion of leading strategists
that such extensive aerial operations, combined
with naval operations, could reduce the most
impregnable naval bases.

Night Facilitates Bombing at Close Range

Night facilitates bombing at very close range.
The aviator can fly close to his target and hit it
in the most vulnerable points.

The first part of aerial attack can be carried

out by surprise, and half of the work is done be-
fore the searchlights and anti-aircraft guns are
put in operation. In a raid of hundreds of aero-
planes the searchlights and anti-aircraft guns
could not cope with the situation. Any plan to
prepare all the naval and militar\^ bases so as
to have sufficient anti-aircraft defenses to cope
with the situation would involve employing tens
of thousands of gunners and their personnel,
withdrawing them from the fronts, and thereby
weakening the German lines.

If the night should happen to be extremely
dark, the aeroplanes could light up the area to
be bombarded by dropping parachute flares.

Need of SilAic^^^to Eliminate Noise of
N. ^)proach

Silencers are needed on aeroplane engines to
eliminate the noise of approach, which is the
only thing that warns the enemy of the ap-
proaching warplanes at night. The silencers
must do their work thoroughly, eliminating the
exhaust sounds entirely, because the anti-air-
craft units have very powerful microphones that
magnify the slightest sound.

Lacking silencers — for no reason other than
the added weight and slight loss of power —
raiding aeroplanes are forced to fly at high alti-
tudes in an attempt to escape detection. The
weight of the fuel needed, and the horse-power
and time spent in evading detection in this way,
represents really a greater loss of efficiency than
the loss caused bv the silencers.

TEXTBOOK OF MILITARY AERONAUTICS

3iIoiuistir, photographed by a French aviator while under fire.

Bombs and Bomb-Holding Gears

The following types of bombs are in use: 16-
poiind bombs, 56-poiind, and 100- and 112-
pound bombs. In some cases there are bombs
weighing 500 pounds or more.

The 16-pound bombs are usually arranged in
series of four under the fuselage. The releasing
^ear is worked from a bowden wire which actu-
.ates a bar releasing the bombs in the following
order: 1, 4, 2, 3, which avoids unequal distribu-
tion of weight. The 56-pound bombs are usu-
ally carried in a series of two, and are released
in the same fashion. The 100-pound and 112-
pound bombs are always carried in single bomb-
frames. These have two levers, one to fuse the
bomb and the other for releasement. These
bomb-frames are usually slung on either side of
the fuselage Ik;1ow the lower plane, and aft of
the axle. In all the above cases the bomb is
held horizontally in a fore-and-aft position, the
nose of the l)omb pointing forward.

In all the latest types of machines the bombs

are carried in a vertical position inside the body
of the aeroplane, nose downward. This is a
ygj.y great saving of head resistance. For ob-
vious reasons it would be inadvisable to give de-
tails of these bomb-dropping devices, which per-
mit the aviator to drop one or all of the bombs
simultaneously.

Dropping bombs weighing 500 pounds or
more is not difficult ; heretofore it has been more
difficult to get large aeroplanes capable of carry-
ing them. Now that large warplanes are com-
ing into use in quantities, the dropping of bombs
weighing 500 pounds or more will be common,
likewise the launching of torpedoes weighing
from 200 to 1500 pounds.

Bomb-dropping with dirigibles differs little
from dropping bombs from aeroplanes, except-
ing that whereas the dirigible makes such a large
target, and moves much slower than the aero-
plane, it cannot come as low as the aeroplane to
drop the bombs. On the other hand a Zeppelin
can carry three or more tons of explosives and
can remain in the air forty hours continuously.

Zeppelin Bomb-Dropping Mechanism

The bomb-dropping mechanism of a Zeppelin
captured by the British was described in a recent
number of the London Sphere. There are sixty
bomb-droppers for conical bombs. The base is
slung in straps, and there is a strap around the
neck. The latter has a releasing hook, and when
the releasing hook is operated, the small end first
drops down and the base slides out of its straps.
The bomb then rights itself and drops base
downward. The bombs are slung in one or two
lines along the under side of the hull. The re-
leasing hook is operated by an electro-magnet,
and there is a small switchboard in the cabin for
controlling the release. Each bomb has a sepa-
rate switch. The bombs can be released by hand
levers also, in case the electric power should fail.
Each bomb has a safety device and is not "alive"
until it has dropped several hundred feet.

Bomb Sights — The Scientific Side of Bomb-
Dropping

Bomb-dropping from heights can only be ap-
proximately accurate. It can be made more ac-

THE WARPLANE FOR BOMBING AND TORPEDO ATTACKS

GettinfT ready to deliver a load of bombs to Gennanv. Adjutant Maneval, of tlu- French Air Serxice, has painted on his aeroplane
the following, '"General Transport Agency— Rapid Service— Delivered at home!" (Official photo.)

curate by the employment of efficient bomb
sights.

A few of the older aviators have learned by
long practice to drop bombs accurately without
sights, but as a general rule one can be more
accurate with the sight than without it. There
are a number of highly ingenious bomb sights
used bv aviators.

Night-Bombing Requires Knowledge of
Aerial Navigation by Instruments

Night-bombing requires considerable tech-
nical knowledge and much actual experience of
aerial navigation if it is to be effective. It is
important that the use of navigating instru-
ments be familiar, and the success of the work
depends obviously upon accuracy.

One of the liundreds of munition depots wliich must be piuli^eitJ iiuui ciitiny bumbs.

TEXTBOOK OF MILITARY AERONAUTICS

Dropping bombs from a French airship at night, depicted by a
French artist.

The instruments used in the British Naval
Air Service for night-bombing are :

Compass — Before starting, the wind-force
and direction are taken. Taking into consider-
ation the height at which the pilot will fly, the
course is plotted, and the pilot then has the
course which he will steer by his compass. Also
he has the course he will steer coming home.

Air-Speed Indicator, or Meter — This is es-
sential because the pilot will throttle down his
engine in order to spare it, and it is essential that
he should know his speed, so that he can calcu-
late by the aid of his cloth at what time he may
expect to be over his objective.

Spirit-Level, or Lateral Inclinometer — This
is an exceptionally useful little instrument, for
as long as the bubble remains in the center the
pilot knows that he is handling his controls in
the correct manner, even though he be on a ver-
tical bank.

Inclinometer — This instrument gives the po-
sition of the machine fore-and-aft, and is quite
useful, as it enables the pilot to determine the

angle at which his machine is either diving or
climbing, or whether he is flying level.

Altimeter — An accurate altimeter is impor-
tant. This will indicate to the pilot the height
above sea-level, and a pilot flying at night
should be well acquainted with the height above
sea-level of all surrounding country, particu-
larly any aerodrome upon which he may be
forced to land.

Night Landing-Lights

In England during the early days of Zeppe-
lin raids, the casualties resulting to pilots who
went up at night to attack Zeppelins was very
high. This was mainly due to two things:
(l) An insufficient number of badly lighted
night-landing grounds; (2) Lack of lighting
devices on the machines.

These conditions resulted in a tremendous
handicap to British pilots. Being out in the sky
at night is worse than being out in a small boat
at night. In moonlight one can pick out places,
but without moonlight flying is difficult. The
safest way is to use a double-motored machine.
Then there is no necessity for hasty landing if
one of the motors develops trouble. Nor must
the pilot forget the recognition signal which he
must flash when he wants to land. This signal
is changed each day.

In addition to the Verys pistol, night flying-
machines are specially equipped with a ])ara-
chute flare. This is fired electrically from the
pilot's seat, through a tube. On release, the
electric connection is made, and the flare, un-
folding a couple of hundred feet, explodes, re-
leasing a small silk parachute with a very bright
light attached. This illuminates the country
for a radius of approximately a quarter of a
mile, and gives the pilot a chance to select a de-
sirable landing-ground. In addition to this,
there are attached to the machine :

(1 ) Holt's Landing-Lights— These are flares
attached to the underside of the wing-tips, and
ignited electrically. LTpon connection being
made, these ignite, throwing a very strong light
downward. This is reflected downward by the
wings, and so does not dazzle the pilot, and if
the ground is practicable for landing, he may
easily make a perfectly good forced landing.

THE WARPLANE FOR BOMBING AND TORPEDO ATTACKS

(2) Electric Headlights — these are not ar-
ranged the same way on all machines. Some
have a single light slung just underneath the
fuselage, and others have one on each wing-tip.
These lamps are merely very powerful automo-
bile head-lamps, very well streamlined, so that
the pilot can switch them on or off at will. They
are used in a similar manner to Holt's landing-
lights. (See chapter on Night Flying.)

Navigation Lights

These are composed of one light in the tail
and one on each wing-tip. The wing-tip lights
show a white light forward, a green light on the
starboard side, and a red on the port side. The
power for these electric lights is obtained from a
small dynamo driven by a miniature propeller.

There is one small disadvantage in the use of
Holt's landing- lights ; that is, if the machine
crashes on landing before the lights have finished
burning, they may very easily set fire to the
whole machine. In using the parachute flare
the pilot should always carry a short stick, about
three feet long, so that in case the flare jams in
the tube, for many reasons, he can poke it
through with the stick, for if he does not, there
is a chance of the flare exploding inboard and
setting fire to the whole machine.

The Sperry Automatic Pilot

The work of the night-bombing squadrons
can be made much easier by equipping the
bombing machines with the Sperry automatic
pilot. How this remarkable instrument can
help is told by Mr. Lawrence B. Sperry, as fol-
lows:

"The most evident advantages that the Auto-
matic Pilot secures in bombarding operations
are the following:

"The facilitating of night-flying.

"The accuracy and simplification of bomb-
dropping.

"The elimination of one man.

"The reduction of physical effort on the part
of the pilot.

"Night-Flying. The bewilderment that
comes on a dark night, due to the pilot's imper-
fect sense of horizontality, is accentuated to a
high degree when he is unable to secure those
visual impressions that he is wont to use in the
daytime. At night the pilot must depend for
his sense of horizontality — experts tell us — on
the reflex actions of certain semi-circular canals
located in the interior of the ears and tactile im-
pressions coming from the nerves, particularly
those in the soles of the feet and other support-
ing portions of the body. It is not generally

^^^

Shaven ^***Mamt?ung

;;emer haven

^•^-^B!

.«t'

.IN

SOME OF THE RECORD

NON-STOP LONG DIS-

TANCE FLIGHTS

Lieut. March*) of French AmTi
Jiue 20, 1916, from Nancy,
over Berlin » dwhn Rnuia,
807 mile*.

Ruth Law, ChiaiD >o Hattiell,
N. Y., Nof. 19, J916, 590 mlle»
in 4 hr*. 17 min. -30 sec

Victor Carlitronii Chicago to Em,
Pa., Nov. 2, 1S16, 452 milas.
Newport Newt to New York,
May 20, 1916, 400 miles.

A. Seguin, duratioB flight _
France, Oct 13^ 1913, 648
miles.

R. Boehm, duration flight —
Germany, July 12, 1914, re.
mained in air 24 hrs. 12 min.

Sketch-plan showing an outline
topographic view of the Allies po-
sitions in relation to Heligoland,
Kiel and Essen. The distance
from the nearest Allied aeronautic
centers on British soil to Kiel is
only about 275 miles. There are
now warplanes which are capable
of carrying over one ton of ex-
plosives over a distance of seven
hundred miles or more, and there-
fore capable of reaching Kiel at
night. One thousand warplanes
dropping a ton of bombs on the
German fleet and U-boat bases
could severely damage the Ger-
man fleet.

TEXTBOOK OF MILITARY AERONAUTICS

A huge mountain of supplies for tlic A..-li: i";., -, (_nriMi::\ hi- ouniu' niountain- "i Mi^ijiiie^ for lirr .-innic^ whirli can
be destroyed by conducting major aerial operations against the German bases, thereby seriously impairing the efficiency of the work
of the German forces.

known that these impressions are susceptihle to
serious error, due to centrifugal force or acceler-
ation pressures, which are capable of reproduc-
ing and even multiplying gravitational sensa-
tions, when the machine approaches an unaccus-
tomed inclination. The misinterpretation of
these sensations has often resulted disastrously.

"Bomb-Dropjnng. In bomb-dropping it is
quite needless for us to discuss the absolute ne-
cessity of having a gjToscopic horizontal refer-
ence plane of integrity and accuracy, or to enu-
merate the inaccuracies to which pendulums,
mercury tubes, and other gravity devices are
susceptible. Our experts have long ago ex-
posed the total unreliability of all of these de-
vices.

"The gjToscopic apparatus is capable of stay-
ing within one-quarter of one degree to the true
horizontal. A sensitive aeroplane is held,
through the intermediary of the servo motor and
follow-up system, within three quarters of one
degree of the position of this gj'roscopic plane.
This variation of three quarters of a degree
might seem to the layman to be, in eflFect, a cor-
responding inaccuracy, but any one accustomed
to reading a baragraph, the index of which is
designed to tremb'e or vibrate constantly, will
appreciate the eas'j and accuracy with which the
pilot bomb-dropper can secure his objective in
the mean of two extreme positions, especially
when close to each other. In this way more ac-

curate results can be obtained than with non-
oscillating conditions, because this motion makes
all the parts of the follow-up mechanism ex-
tremely sensitive, as in the case of the baragraph.
Furthermore, the slight motion assures the op-
erator that the apparatus is functioning prop-
erly, while he need only consult his clinometer,
located on the g>'ro unit, to check up accuracies.

"The proposition to connect the bomb sight
directly to the gj^roscopic element involves ham-
pering its freedom by friction of the connection
links, and by the inertia vibrations of the sight;
in addition, pressure of the hand in making ad-
justments is likely to cause inaccuracies. It
is always advisable to leave the gyro as free and
unmolested from outside forces as possible.

"With the bomb sight rigidly fixed to the side
of the machine or to the floor, the method of
sighting is somewhat as follows:

"With the gyro manual-control the position of
the aeroplane is adjusted until both clinometers
read zero. The operator then seciu-es by his
rudder the motion of some objective in his field
of vision, parallel to the longitudinal cross-wire.
During this time the deviation angle is set by
taking the usual stop-watch reading, or by other
steps involving this very simple oijcration. The
pilot bomb-dro])per has now only to keep his
ultimate objective moving along the longitudi-
nal wire, before releasing the bomb when it
reaches and crosses the lateral wire.

THE WARPLANE FOR BOMBING AND TORPEDO ATTACKS

27,

i' "The increased accuracy of bomb-dropping
from an aeroplane equipped with the Automatic
Pilot is due to:

"1. Being able to get the aeroplane more ac-
curately lateral over the target.

"2. Being able to release the bomb at the
proper angular distance from the target.

"3. Simplifying the operation of bomb-sight-
ing, since the sight is held automatically and ab-
solutely horizontal, the reby allowing the pilot
bomb-dropper to focus his entire attention on
adjusting the sight and steering the aeroplane.

"During the long night bombardments, the
elimination of the extra passenger has the ad-
vantage of either increasing the radius of action
or of enlarging the bomb-carrying capacity of
the machine; while, of course, in the event of
failure, one man is lost instead of two. The
physical work of which the pilot is entirely re-
lieved in long bombardment trips, especially

with the larger types of aeroplanes, would fre-
quently be too much for the ordinary pilot."

Turn into the Wind to Avoid Drift

In bombing-raids drift is one of the most dif-
ficult factors to conquer by the use of instru-
ments, because of the difficulty of calculating
with accuracy, especially at night. There is a
simple solution to this problem, however, which
is always to turn into the wind when about to
drop the bombs, and thus avoid the drift en-
tirely.

Formation for Bombing Raids

Suppose one thousand large bombing ma-
chines were sent to bomb Kiel, Essen, or any
other important German base. They would
probably set out from five to ten aeronautic

An official air-photopraph of Ostend after the Rritisli naval bombardment. It will be seen that the bombardment was directed
against the Germans' submarine lair, the letters indicatinft the principal hits. Thus B represents the damaged entrance pates to
basin; C, Q and R, destroyers struck; D, U and Z, pier and jetties hit. The other letters indicate damage to the submarine har-
bor and adjacent buildings. Ostend is an important German naval base.

TEXTBOOK OF MILITARY AERONAUTICS

bases, on carefully drawn plans. As there
would be no advantage in having all the ma-
chines arrive at the same time, since there would
be possibility of confusion and crowding, the
plan would probably be to divide the thousand
aeroplanes into from six to ten wings, each wing
to consist of a given number of squadrons in
charge of a squadron commander.

The raid would have to be carried out in the
darkness between sundown and sunrise. In the
autumn, winter, and spring, when the nights are
longer, such raids can be conducted entirely un-
der cover of darkness, and the raiders have little
to fear from anti-aircraft guns and enemy air-
craft. In the first large night-raid, made in
August, 1917, by 232 Italian aeroplanes, only
one machine was lost, the others being protected
by darkness.

In a raid of a thousand aeroplanes, the best
effect can be obtained by sending units of 200
to follow each other at intervals of half an
hour. The second imit arrives after the first
unit has done its work, and finds the theater of
war ablaze with the fires started by the first
unit. ^ The lights assist in picking out the im-
portant points and objects to be bombed. The

succeeding units find their work correspond-
ingly easy.

Rules for Formation Flying

The rules for formation in this case would be
the same as prescribed by the General Stafi" of
different countries. These are practically uni-
form, since each country adopts improvements
as fast as they become known, which happens
whenever a squadron or flight commander is
brought down and printed or written instruc-
tions are found on his person.

The instructions of the British General Staff
to squadron and flight commanders of bombing
units — which are also applicable to fighting,
reconnoitering, photographing, and other
branches of the air service, are as follows:

A leader must be appointed, and a sub-
leader, in case the leader has to leave the forma-
tion for any reason; i.e., engine trouble.

The leader cannot efficientlj^ control more
than a certain number of machines. If, there-
fore, this number is exceeded, the mission must
be carried out by two formations acting in con-
cert, but each with its own leader.

A French BrcKUct tractor binlune used fur buiiibing, photographing and artillery spotting.

THE WARPLANE FOR BOMBING AND TORPEDO ATTACKS 29

Drawn by Frank ilerritt Courtesy of Motor Boating

Reducing the German fleet at Kiel with present day warplanes.

TEXTBOOK OF MILITARY AERONAUTICS

How 1000 Warplanes Could Raid Kiel

Suppose 1000 warplanes were to start from
the Allies' lines in a major operation against
German bases. They would start from differ-
ent aerotlromes, probably about one hundred
from each aerodrome, the machines following
each other at intervals of 30 seconds.

Squadrons of 2.5 machines would probably be
fonned, with a flight commander to each squad-
ron, who would start first. The aviators of each
squadron would follow as fast as possible, each
aviator following the navigation lights of his
s(juadron commander. A prearranged signal
from the aerodrome woidd tell the squadron
commander when the last machine of his squad-
ron left the ground, and he would then, after a
brief delay to give time for the machines to
climb up, give the signal to fall in line, and the
squadron would travel on in V formation.
Every aviator, of course, would have studied
the specially prepared chart and would be fa-
miliar with the route — as it looks to the aviator
from the air.

Thus they would travel the 450 or so miles
between the Allied bases and the German naval
bases, or about the same to the important Ger-

man militarj^ bases. There being a crew of
three men to each warplane, the aviators would
not be as lonesome as they often are in bombing
raids alone.

The distance woidd be covered in five to
six hours. And then? Then, with the tor-
pedoplanes attacking the German ships from
the sides and the bombs attacking from above,
the hardest blow yet struck at Germany, the
most effective blow in the fight for humanity's
rights, would be struck!

Just as the battles of Manila, Santiago, and
Tshushima lasted only about an hour, so the
battle of Kiel would be over in one hour, because
the destruction of the German fleet from the air
would make it possible for the Allies' mine-
sweepers to clear away the German mines and
open the way for the Allies' ships to deal with
U-boats in their bases at close range. And
Germany's naval power would be crippled
thereby — and its total destruction would follow,
through repeated raids on the less important
U-boat bases.

So let us not lose a minute ; let us concentrate
the nation's efforts on turning out the thousands
of torpedoplanes and warplanes needed.

Five different sizes of bombs dropped from aeroplanes. The weight of aeroplane bombs to-day varies Irom Hi to oOO pounds.

CHAPTER III

DROPPING BOMBS FROM AEROPLANES

By Jean- Abel Lefrance

Last February a French aviator, Captain
Guynemer, succeeded in bringing down inside
the French lines, one of a raiding squad of 20
German bombarding planes of the newest type,
manufactured by the Gotha Wagonen Fabrik.
A peculiarly interesting feature of the aeroplane
was its Goerz sighting telescope or range-finder,
designed to facilitate the taking of correct aim
at objects to be bombarded. A careful study
of this, with a discussion of the laws governing
the dropping of bombs, appears in "La Nature"

(Paris), together with the accompanying dia-
grams.

Any projectile dropped from a height is sub-
ject, of course, to two constant forces, the re-
sistance of the air and the acceleration due to
gravity. Its trajectory is a vertical line from
the point of discharge. A, to the striking point,
B (Fig. l) . If the bomb be dropped from an
airship in motion, it will have an initial speed
equal to and in the same direction as that of
the latter. This new force is compounded with

TEXTBOOK OF MILITARY AERONAUTICS

Inae.x and bti5e 6

Index I

CrortoaraY>h

Uo.versol j-^tnt

Eut-pieccfJt— ■

Chronograph

Controlling
Disk for Prism

Rodcontrollinq
PrI.rr. ^

Fig. 1. Trejectorj' of a bomb falling
from an aeroplane as affected by the di-
rection of the wind.

Fig. -2. The Goerz range-finder.

Fig. 3. Diagram showing construction of
the Goerz range-finder.

the two former, and the result is the curved
trajectory' A C.

If this bomb, having a given initial velocity,
is dropped into a layer of air in motion, that
is, into the wind, it is acted on by the latter,
and is said to undergo "drift." If the wind
is at the back, the trajectory is lengthened, as
in A D; if there is a head wind, the trajectory
will be shortened, as in A E.

If the bomb be dropped from an avion which
the strength of the wind causes to be stationary'
with respect to the ground, i.e., when the ve-
locity of the wind is exactly equal to that of
the avion and in the opposite direction, the
projectile will have no initial velocity and the

curve of its trajectory will be a function solely
of the drift produced by the wind, as in A b;
it will therefore fall to the rear of the point of
departure. This latter case, however, is ex-
ceedingly rare, since it presupposes a wind of
120 to 1.50 kilometers per hour; but this is a
gale too high to permit the sending up of avia-
tors.

These trajectories being given, the angle of
aiming will be the angle formed by the vertical
line A V at the point of departure A with the
straight line joining this point A with the strik-
ing point O, i.e., the angle VAO.

Since these trajectories are curves, the height
of the avion above the object aimed at is an
element which modifies the value of the trajec-
tory. Since the wind causes drift, this drift will
vary with the form of the projectile and with
the velocity of the fall. Here we have two ele-
ments which are constant for each type of bomb.

To sum up, the trajectory of a bomb dis-
charged from an avion is the resultant of the
following forces:

Weight

Form
Drift
Speed of avion in
wind

Elements constant for a given type of
bomb

Considered as a constant for
a given type of avion

A Vobin bombing machine u^cU bj Uic llusslunii and Uic French.

Other Elements
Height of shot
Initial speed of bomb, i.e., of avion

with respect to ground
Velocity of head wind

Variable
elements

DROPPING BOMBS FROM AEROPLANES

Of these three principal variable elements
which it is necessary to know for each case of
bombardment, one of them, the velocity of the
head wind, can be immediately deduced when
the velocity of the avion with reference to the
earth is known, since this velocity of the wind
is the difference between the velocity of the
avion with respect to the earth and its normal
velocity in the wind, an element which is fixed
for a given type of avion.

Take an avion having a normal speed of 150
km. per hour; if it is only going 100 km. per
hour with reference to the earth, then it is fly-
ing against a head wind of 50 km. per hour.
Hence it is only necessary to know the height
of the avion and the initial speed of the bomb
to determine a trajectory. This method of cal-
culating trajectories seeks to base itself on
science in order to obtain a mathematical pre-
cision in its results. Unfortunately it is based
upon a probable knowledge of atmospheric con-
ditions, which are essentially capricious. Par-
ticularly, the speed of the wind at the height of
the avion is taken into account, e.g., at 4000
meters, but it is supposed that this remains
unmodified down to the ground, which is rarely
the case in reality. It may also be that, starting
from 3000 meters, the wind changes its direction
so much that the best calculations, the best tele-
scopes, and the best bombardiers, are unable to
secure a correct aim, so that some authorities
despair of ever being able to get results in aerial
bombardment comparable to the efforts made.
Goerz Range-Finder. — This is certainly the
test and most highly perfected effort of German
science to find means of destroying railroads,
factories, and populations outside the range. of
their big guns. It consists of a telescope about
■one meter long; mounted on a universal joint, it
can be oriented in every direction and kept
strictly vertical whatever be the position of the
•avion (Fig. 2). The accompanying diagram
(Fig. 3) shows the ensemble of the optical sys-
tem; the field obtained is 500/1000 and the en-
largement is 1.5.

At the base of this telescope is a prism
mounted on a pivot and controlled by a grad-
uated disk. The telescope remaining vertical,
the play of the prism permits the visual ray to

Direct to*^ o^ ^ovKmcrtt of Airopfortc^^

Figs. 4, 5, 6. Direction of aim in the finder.

be inclined a number of degrees corresponding
to the graduations of the disk.

On this disk are two indexes, one correspond-
ing to the vertical speed, or dead point of the
range-finder, and the other to the vision of 22°
30'. Another index serves as a basis ; it is fixed
on the body of the range-finder. At 0° the
marksman sees the ground along the vertical
(Fig. 4) ; at 20° the inclination of the visual
ray is 20° in front of the avion (Fig. 5) ; at 5°
the inclination is 5° behind the avion (Fig. 6).
A small index is movable upon the disk, but
this can be made solid with it bv means of a little

Three different types of bombs dropped by Allied aviators at
Salonica.

TEXTBOOK OF MILITARY AERONAUTICS

I Ignilion

Device

Thermtt

Reiinoui
matter

MclUo

nkite
piosphonm

Section of Incendiarj- Bomb dropped from Zeppelins. The
Incendiarj- bomb illustrated herewith is being used by German
airships for the purpose of setting afire enemy towns and mili-
tarj' establishments; it is described in a poster published by
the British Fire Prevention Committee as follows: "The usual
fire-bomb dropped by a Zeppelin is of conical shape, the diam-
eter at the base being about ten inches. It is wrapped round
with inflammable cord, which gives it rather a nautical appear-
ance, enhanced by a handle at the apex for lowering it over the
gunwale of the airship — if airships have gunwales. The base
is a flat cup, and from this to the handle runs a hollow metal
funnel forming the center and business part of the bomb. This
center funnel is filled with thermite. Thermite is the prepara-
tion which on ignition produces a heat so intense as to melt steel.
The ignition of thermite creates a tremendous glare of light,
and the heat melts the metal funnel. The molten metal spreads
when the bomb strikes. It sets up at once a fierce fire if it
strikes anything combustible, but at the beginning it is only a
small fire, and if it is tackled at once with water it can be put
out before it does any damage to speak of.

detent. This index once fixed before a gradu-
ation of the disk, after passing the dead point
falls into a small notch, and thus informs the
gunner that he sees the ground according to the
inclination which he had marked with this index ;
this is disengaged by a slightly stronger pres-
sure of the hand.

In the body of the telescope is a spirit-level.
The edges of the air-bubble are refracted in such
manner that they ap})ear in the form of a black
circle, which sen'es as a sighting center for the
telescope. In the course of all his range-finding
operations the gunner must keep this bubble in
the center of the ocular, which will keep the

range-finder vertical no matter what the inclina-
tion of the avion.

The universal joint permits the finder to in-
cline freely from right to left or from front to
rear, but when it revolves around its vertical
axis, i.e., when the visual ray, instead of being
directed in front of oi- behind the avion, is di-
rected to the right or the left of the route fol-
lowed, the finder acts upon a route corrector.
This consists of an electric device. Resistances
act upon a very sensitive galvanometer placed in
front of the pilot and indicate to him how to cor-
rect his route in order to make it pass exactly
above the object to be bombarded.

Method. — There are only a few of the ele-
ments constituting a trajectory which can differ
in the course of each bombardment: the height
of the avion above the object, the initial velocity
of the bomb, the speed of the wind. The Ger-
man method of the Goerz finder enables a calcu-
lation of these three elements to be made.

1. The height is obtained by subtracting from
the altitude range shown on the altimeter of the
avion the altitude of the object bombarded; e.g.,
if the avion is flying at 4200 meters above sea-
level, and if the factory to be bombarded is 200
meters, then the height to be reckoned with will
be 4200— 200— 400€ meters.

This method, moreover, is subject merely to

ii ivu iu a

stuck of Imy on EiigliUi wil.

DROPPING BOMBS FROM AEROPLANES

very slight errors where high altitudes are in
question. Example: At 90 km. an error of
altitude of 500 meters for an avion at 4000
meters, corresponds to an error of only 25
meters at the ground level (Fig. 7) .

2. Initial Velocity of the Bomb. — In reality
this is the speed of the bomb with reference to
the ground. This element is the most difficult
to know, because it varies with the velocitj^ of
the wind, which is in a state of perpetual insta-
bility. If an avion possesses a speed of 150 km.
and the wind is blowing at the rate of 50 km.,
then with a following wind the avion will travel
at 200 km. per hour, while with a head wind it
will go only 100, This difference of speed con-
siderably modifies the trajectories, as can readily
be seen by examining the curves in Fig. 7, in
which the avion is going 120 and 60 km. per
hour respectively. In place of being simply
added or subtracted, this speed of the wind and
speed of the avion may be compounded if the
avion receives the wind, for example, three quar-
ters to the rear (175 km. per hour) or three
quarters head on (125 km. per hour) .

In principle, to simplify the calculations, the
avion should bombard with the wind head on,
i.e., with the speed as much reduced as possible.
To determine this kilometric speed of the avion
we calculate the time required by a fixed point
on the groimd O to traverse an angle fixed at
45° or 22° 30'.

It is easy to see by the figure that the time
required by an avion to find the range of the the initial horizontal speed of the bomb
same point successively, first
with an angle of 22° 50' and then
vertically, is proportional to the
speed of the avion with respect
to the earth. A value in sec-
onds is obtained.

A previous prepared table
will indicate that if the avion be-
ing at an altitude of 4000 meters,
a point on the ground takes 36
seconds to pass through an an-
gle of 22° 30', then the avion is
going 100 km. per hour, with
reference to the earth; if the
point takes only 18 seconds to

pass through the same angle, the A bomb liropped from a Zeppelin,

Another Speriy bomb sight which practically does all
thinking necessary for accurate bomb-dropping.

avion is going 200 km. per hour. This value is

TEXTBOOK OF MILITARY AERONAUTICS

woo

'^iOOO

100 300jMtociM$eonetMt«c loaei

•A
I o

1 '

\ V

3000

too 300 300 4O0 SOO 600 700 800 900 fOOO
Oev.alion m Meters

Fig. 7. The falling curves of bombs at different speeds.

D-recliOrt Control
Gurtoe>-'» seot

Fig. 8. Location of the finder upon an aeroplane.

3. Moreover, it is known that avions of the
Gotha type have 150 km. per hour speed when
the motors are revolving at their usual velocity ;
if the preceding range-finding shows the speed
at the ground to be only 100 km. per hour, the
obvious deduction is that the head wind has a
value of 50 km.

Thus all the elements of the trajectory sought
are known ; it remains only to read on the chart
which firing angle is suitable to cause the Iximb
to fall on the given object, in view of the given
elements.

Several minutes before arriving over the ob-
ject to be bombarded it is necessary to ac(}uire a
knowledge of two elements which will enable
the gunner to read on the chart the proper
firing angle. The altitude range on the ba-

Fijr. 9. Device for releasing bombs.

rometer less the altitude of the object gives the
height of the fall of the projectile.

To obtain the second element, which will give
a knowledge of all the values of speeds, we
have recourse to the method of previous range-
finding of the ground, explained previously.

The index of the graduated disk is fixed at
22° 30'. The range of any point whatever on
the ground forward of the avion is found — a

Bombs in the fuselage of an aeroplane.

DROPPING BOMBS FROM AEROPLANES

A 100 11). bomb dropped by a Zeppelin.

route perpendicular to the one followed, a river,
a house, the edge of a wood. This point is
caught in the circle formed by the air-bubble
and followed while turning the disk until the
index falls into the notch at the dead point; at
this instant the seconds chronograph is re-
leased and the terrestrial point continues to be
followed in the range-finder until the 0° of the
disk is checked at the dead point. The chrono-
graph, immediately stopped, gives a number
of seconds which, when found upon the chart
in the line of altitude, indicates the speed of the
avion with respect to the ground and the sight-
ing angle to make use of, for example, 10°.

The index is immediately set at the number
of degrees of the sighting angle, i.e., 10°. The
observer is ready to operate. About 2 or 3 km.
before flying over the object the latter is caught
in the field of vision, then in the circle of the
bubble. At this instant the route corrector op-
erates and the galvanometer indicates to the
pilot whether he is following a route which will
make the avion pass directly above the object.

At the precise moment when the index fixed
at the number of degrees of the sighting angle

falls into the notch at the dead point, i.e., at
the moment when the finder aims with an angle
of 10°, the bombardier operates the bomb re-
leaser and the bombs fall toward the object.

Throughout the whole bombardment the pilot
must keep his craft strictly head on to the wind ;
the air-bubble must be kept rigorously in
the center of the ocular, the play of the
prism alone serving to seek the object.

This Goerz range-finder is of an elementary
simplicity for any one who has manipulated it
in a few brisk actions. Its movable prism en-
ables the object to be found with ease, and its
annular bubble permits it to be immediately
centered in the vertical position. Marvelously
constructed, it appears to show marked prog-
ress over all previously made range-finders.

It eliminates errors, except from new and
practically incalculable elements, such as varia-
tions of forces and directions of the wind be-
tween the altitude at which the sighting is done
and the ground, or when it becomes impossible
to keep the avion head on toward the wind.

American-made Barlow aircraft bombs. Photo courtesy
New York Times & Western Newspaper Union

TEXTBOOK OF MILITARY AERONAUTICS

The aim being at times scientifically perfect,
as the application of a method derived from
calculations, does it follow that the bombs will
fall directly upon the objects aimed at? Re-
sults loudly proclaim a negative. Hundreds
of bombs discharged on railway stations, on

famous ironworks, on important aviation ter-
rains, have been without result, except for a
few shell "funnels" in the ballasts, a few labor-
ers killed, some holes in hangars. Range-find-
ing is a delicate task to execute in an avion sur-
rounded by bursting shells.

^Memoranda :

The master of the air. A Voisin armed bombardment machine equipped with aircraft gun of large caliber photographed in mid-
air. This machine is equipped with a Canton-Unne motor.

CHAPTER IV

BATTLEPLANES AND AIRCRAFT GUNS— THE DOMINANT FACTORS IN
MAINTAINING THE SUPREMACY OF THE AIR

Supremacy in the air, the all important fac-
tor which leads to victory on land and sea, de-
pends greatly on battleplanes and aircraft
guns.

About twenty per cent, of the service aero-
planes used by the warring nations at present
are the very fast avians de chasse or pursuit ma-
chines used exclusively for fighting; seventy
per cent, are the slower types used for regulat-
ing artillery fire, aerial photography, scouting,
and in connection with infantry and cavalry
operations; five per cent, are the slower, large
bombing aeroplanes. All of these aeroplanes
carry machine guns ; some carry cannons.

Proportions of Different Types of Armed
Aeroplanes in the Air Service

The proportions vary continually in accord-
ance with developments, and the future will see
an increase in the number of bombing machines,
with possibly an increase of fighting machines.
Raiding from now on is to be carried out more
and more extensively, and in connection with
the protection of bombing planes, as well as the
protection of artillery "spotters" and photog-
raphy planes, aerial fighting will increase.

Pursuit machines will always be needed to
fight enemy aviators, but the practice of send-

TEXTBOOK OF MILITARY AERONAUTICS

ing pursuit machines to protect the artillery
spotters and photography planes will grow
less and less, because it is more economical to
employ large machines capable of carrying two
or more guns and to defend themselves.

Otherwise it is hard to protect a plane with
less than four to six fighting machines. To pro-
tect themselves these planes must carry from
three to four guns. JNIany a photography
plane, equipped with only one gun, has been
brought down by an enemy aviator who darted
at it suddenly and riddled it with shots while
the observer was taking photographs and did
not see it approach.

Therefore a change is taking place toward
larger machines to do this work, which are ca-
pable of carrying three to four guns.

The Five Fundamental Factors in Maintain-
ing Supremacy in the Air

The five fundamental factors in maintaining
supremacy in the air are:

(1) Speed.

(2) Position of the aeroplane.

(3) Skill in piloting the aeroplane and in
manipulating the guns.

(4) Number of aeroplanes.

(5) Destructiveness of the projectiles.

Speed is incontestably the most important
factor. The value of position as a command-
ing factor was first demonstrated by the fa-
mous German aviators. Captains Boelke and
Immelmann, who would climb high and take a
position as near as possible to a cloud. There
they would wait for an Allied aeroplane, then
dive down towards it, firing the machine gun
at the same time. If they missed their prey,
they would not attempt to challenge the Allied
aviators or to manceuver to a commanding posi-
tion and give battle. Failing in their first dive,
they would land and go up again later to try it
all over. It cost the Allies a great many avia-
tors and aeroplanes before thej' found out the
value of position as a fundamental factor in
maintaining supremacj' in the air.

A 37 millimetre Hotchkiss cannon mounted on tt French "\'oisin" battleplane.

BATTLEPLANES AND AIRCRAFT GUNS

The famous French aviator Vedrines examining the two guns of a German battleplane, which are so mounted that they can be shot

in a half circle and up and down — -through the hole in the fuselage.

Skill is an important factor, and often makes
it possible for an aviator whose machine makes
five miles less than his adversary to fight on an
equal basis.

Number makes up for lack of speed or posi-
tion. Having two or three machines to the
enemy's one, makes up for the handicap due to
lack of speed.

Destructiveness of projectiles is a very im-
portant factor. The bullet of a machine gun
must strike either the pilot, or the propeller, or
the motor, or the gas tank, or the control wires,
to put the machine hors de combat. The shell,
on the other hand, will put the machine hors de
combat if it strikes practically any part of the
machine.

Types of Aeroplanes and Their Armament

The types of aeroplanes used by the warring
countries, and their armament, have been

changing continually. At the date of writing,
the following types are used:

Avions de Chasse or Combat Machines

(1) The "Spad" carrying one or two pas-
sengers. A number of these machines have, un-
fortunately, fallen in the hands of the Germans,
so we may say that their horse-power ranges
from 150 h.p. to 250 h.p. and are equipped
with Lewis and Vickers machine guns.

They are used extensively by the French.

(2) The "Nieuport," one passenger,
equipped with one 110-horse-power Le Rhone
motor, capable of a speed of 150 kilometers per
hour; equipped with two and three Vickers or
Lewis machine gun synchronized to shoot
through the propeller.

(3) The "Avro," carrying one or two pas-
sengers, equipped with one lOO-horse-power
Gnome motor, carrying one or two gims.

TEXTBOOK OF MILITARY AERONAUTICS

The A. E. G. 1917 single motored type of German biplane,
equipped with a 175 h.p. Mercedes motor.

Avions Types "Corps d'arme" — Used for
Spotting Artillery Fire, Aerial Pho-
tography, Etc.

(4) The "Caudron" G-4; pilot and ob-
sen'cr; equipped with two 80-horse-power Le
Rhone motors, Lewis and Vickers guns forward
and rear.

(5) The "Caudron" G-6; two passengers;
equipped with two 110-horse-power La Rhone
motors, carrying one machine gun forward and
one in the rear.

(6) "Dorand" A-R; two passenger;
equipped with one 150-horse-power Hispano-
Suiza motor or a 170-horse-power Renault,

carrying one Vickers gun forward, and two
Lewis guns in the rear.

(7) Farmaii; pusher type, two passenger;
equipped with one 170-horse-power Renault
motor, carrying one or two Lewis guns for-
ward.

(8) Morane Parasol; two passenger; one
110-horse-power La Rhone motor, mounting
one Lewis gun in the rear.

(6) Caudron R-4; three passengers;
equipped with two 150-horse-power Hispano-
Suiza motors, with two Vickers guns mounted
forward in turrets, and two Lewis guns in the
rear.

(9) Letort; equipped with two 150-horse-
power Hispano-Suiza motors; two Vickers
guns mounted forward in turrets and two
Lewis guns in the rear.

(10) Moineau; three passengers; one 220-
horse-power Samson motor, connected to drive
two propellers; equijiped with two Vickers
guns mounted forward in turrets, and two
Lewis guns in the rear.

(11) Sopmth TripMue. This type of
machine has, unfortunately, fallen in the
hands of the enemy, therefore we may note its
existence as a combat machine used by the
British.

(12) Sopwith biplane; two passenger;

A "G-4" Caudron biplane, equipped with two HO li.p. I>e ithone motors. The gun mounting is si-rn in front.

BATTLEPLANES AND AIRCRAFT GUNS

The ofScers of a squadron of Voisin bombing ma chines being decorated for their successful raids.

equipped with 130-horse-power Clerget motor,
carrying eight bombs; Vickers machine gun
forward, shooting through propeller, and one
Lewis gun in the rear.

(13) Voisin-Peugeot; two passenger;
equipped with a 220-horse-power Peugeot mo-
tor ; carrying two Vickers or 37 millimeter guns
forward.

(14) Breguet-Michelin; two passenger;
equipi^ed with one 220-horse-power Peugeot
motor; mounting two Vickers or 37 millimeter
machine guns forward.

(15) Farman; pusher type, two passenger;
equipped with one 170-horse-power Renault
motor, mounting one Lewis gun forward,

(16) The Caproni; the various tyjies men-
tioned in the chapter on "Warplanes for Bomb-
ing and Torpedo Launching," are with Fiat
machine guns and cannons and Davis non-re-
coil guns. So are the Pomilio SIA, Sa-
voya-Verduzio and ]Macchi machines.

At date of writing, the British, French, and
Germans can be said to have more or less the

same types of aeroplanes, with the same amount
of armament. As a matter of fact, the warring
nations are never far from each other in either
types or armament, because as fast as they cap-
ture each other's machines and find important
improvements, they copy them.

Pursuit, or Combat Machines

Among the comparatively new machines of
the British Royal Flying Corps, there is the
Soptiith triplane, which has given such a good
account of itself as a combat, or pursuit ma-
chine on the Western fronts. Other machines
of this type are the De Haviland scout biplane,
a "pusher" with a fixed gun in front, and the
Vickers biplane, two passenger, equipped with
Beardmore or Clerget motors.

The German combat machines include the
Ago, the Fokker, the Halberstadt, the Roland,
which are equipped with Mercedes, Oberunsel
(rotary), Benz, and Argus motors of 165 to
175 horse-power. They are armed with Para-
beilum or Vickers and Lewis guns.

"Two Tails," twin fuselage simple mo-
tored German Ago biplane equipped with
a 150 h.]). Benz motor and Parabellum
and Vickers guns.

TEXTBOOK OF MILITARY AEROXAUTICS

The Gentian "Rump'

liipbmr, I «(i-seater, equipped with two iruns.

The two smallest machines, the Halberstadt
and the Albatros Bii, are single seaters, all the
others being two-seaters. Where the gunner
occupies the rear cockpit, it is found that in
many cases the pilot is equipped with a syn-
chronized gun, fired forward and sighted by
steering the machine itself. The same applies
to the single-seaters. Some of the single-
seaters are equipped with two synchronized
guns, fired directly in front. The top wing of
the Albatros Bii is 28 feet, 4> inches, the bot-
tom wing 26 feet, nine inches ; gap, 5 feet, three
inches; chord, five feet, nine inches; length over
all, 24 feet. The measurements of the Hal-
berstadt are: top wing, 28 feet, 6 inches; bot-
tom wing, 26 feet; gap, four feet, 6 inches;
chord, 5 feet; length, 24 feet.

The measurements of the Nieuport and the

Spad are: Nieuport; top plane, 24 feet 6 inches;
bottom plane, 23 feet; chord, top plane, 3 feet
11 inches; bottom plane, 2 feet 4 inches; gap, 4
feet 2 inches to 3 feet ii inches; length, 18 feet
6 inches. Spad type 5 VII, one passenger; top
plane, 25 feet 8 inches; chord, 4 feet 7 inches;
gap, 4 feet 10 inches; length, 20 feet.

The speed of these machines varies with the
horse-power, ranging from 95 miles to 125 miles
per hoiu" high speed, to from 56 miles to 80
miles slow speed. The climbing speed ranges
from 4000 to 10,000 feet in ten minutes.

Owing to lack of demand, few machines of
this type were built in the United States until
recently. But efficient types existed. The Cur-
tiss wireless scout of 1915-16 was followed by
the Curtiss triplane, the characteristics of wliich
cannot be made public.

The Italian I'onillio curiibat plane, salU tu be tlie fu«tei>t buttlcplune in vxititence. (Uliieiiil Ualian Photo.)

BATTLEPLANES AND AIRCRAPT GUNS

The German "Spatl," tlie

MflTelU-.s lliolill'cil "\ll];lil

nized to shoot through the propeller.

It carries two Maxim guns which are synchro-

The Triplane — A Scientific Solution of the

Problem of Getting Speed and High

Factor of Safety

The triplane solves the problem of getting
high speed with the low landing speed and high
factor of safety. The additional plane affords
sufficient increase in carrying capacity to lift the
additional weight of stronger construction, and
also makes slower landing possible, without
much additional head resistance.

The battleplane, while representing only one
fifth of the types of machines used in the pres-
ent war, is the key to command of the air, be-
cause the skies must be cleared of enemy avia-
tors before the scouts, bombing, artillery, and
infantry aeroplanes can w^ork efficiently. Of
course, if one side could outnumber the other
side, the equivalent of the fighting power af-
forded by the fast battleplanes could be obtained
by the advantage afforded by number, which
makes up for having a few miles less in speed
or less skilful aviators.

But neither side has been able to outdistance

the other appreciably in numbers; therefore
command of the air is still decided by speed, the
pilot's skill, and the pilot's ability to gain an
advantageous position, like the famous Captain
Boelke, who used "position" as a winning fac-
tor.

As a general rule, however, speed is the basic
factor for achieving command of the air.
Hence every effort is made to get speed, and the
factor of safety in construction is only given
second consideration, when it is considered at
all.

Triplane Safe, Even if Wing Is Shot Away

The triplane is safe, even if a wing is shot
away; the remaining wings will support it for
the rest of the flight under any normal condi-
tions. A biplane usually collapses soon after
a wing has been shot away, and a monoplane
collapses immediately.

Triplane construction removes the speed
limitations imposed upon the small biplanes and
monoplanes by their limited lifting power;

TEXTBOOK OF MILITARY AERONAUTICS

A squadron of Xicuport combat machines.

therefore speed can be increased to close to 150 ment just in time to avoid a collision. One of

miles, going beyond the margin of safety of
the average biplane battleplane.

Battleplanes that Collapsed in the Air —
Loss of Factor Safety Not Compensated

A recent despatch stated that German bat-
tleplanes have been collapsing in the air, at

the wings of the British aeroplane, however,
scraped one of the German's wings, whereupon
the latter began to fall. The British pilot
dived after him and was startled to see the
German's damaged wings fly completely off,
while the tail dragged as if its back was
broken."

The causes are evident. In the struggle for

times without being hit, often when but slightly additional speed, there has been sacrificed the

damaged. The despatch follows in part:

"With the British armies in France, via Lon-
don— British pilots continue to bring in ac-
counts of German aeroplanes breaking to pieces
in the air soon after being attacked. That

factor of safety. The machines are merely
shells of machines.

Triplane construction is a scientific solution
of getting greater speed and high factor of
safety, but there is, of course, nothing to pre-

tendency has been notable for more than a fort- vent cutting down the factor of safety, so as to
night. Once shot out of control, the German get a few miles more in speed,
aeroplanes have lost their wings, tails, and other Considering the fact that low factor of safety
gear to such an extent that when they finally involves the loss of aviators and machines
crash on the ground, very little wreckage can through accidents, as well as through machines
be seen. collapsing when slight damages are inflicted by

"A British pilot recently flew at an enemy gun-fire or other causes, and that this loss in-
machine head-on, manoeuvering at the last mo- volv^es a decrease of skilled aviators and number

of machines, the writer contends that
this loss is not compensated for by the
advantages afforded by the slight gain
in speed. As already pointed out,
while speed is the most important fac-
tor in maintaining supremacy in the
air, five miles or so less speed than
that of the adversary' can be compen-
sated for by having skilful aviators, or
The Gennan "Koiaiui" two siaiir, so imiit thai the i>iiot .scc-s ovlt tho jj greater nimibcr of aviators and aero-

npprr plane and hag but a single stmt, like the "wireless" Curtiss of 1916. .

It U equipped with • 140 h.p. Bcnz motor. plones.

BATTLEPLANES AND AIRCRAFT GUNS

Triplanes being assembled at one of tlie Sopwith factories in Eiighiiul, being inspected by tiie King and Queen of England.

These triplanes are equipped with 130 h.p. Clerget motors.

Large Aerial Destroyers

The larger army machines are four: The
"Moineau," the "Voisin-Peugeot," the " Bre-
guet-JNIichelin" and the "Farman." These
may be called "destroyers," no matter what they
may be used for. The most popular British
machine of this type is the "Handley-Page."
This machine is equipped with two twelve-
cylinder Rolls-Royce cylinders of 280 horse-
power each; the top wing has a 98-foot span;
the lower wing, 65 feet. It has mountings for
three Lewis guns.

The Germans have several machines of this
type. The twin "A. E. G." (manufactured by
the Allegemeine Electricitats Gesellschaft) is a
three-seated tractor biplane with two i80-horse-
power Mercedes motors. Like all machines of
this type, including the French, British, Italian,
and Russian, it is equipped with two pairs of
wheels. Its armament consists of Maxim guns
forward and rear, and a bomb-dropping device
in front of the passenger's seat.

The "A. G. O.," a twin-bodied pusher,
usually equipped with a single Bentz 175-horse-
power motor; the latest are equipped with a

Bentz 220-horse-power motor. It carries two
guns mounted on turrets in front.

The twin-motored 520-horse-power "Gotha"
is a three-passenger biplane usually equipped
with two six-cylinder Mercedes motors of 260
horse-power. The wings are 76 feet in span.
The length of the machine is 38 feet. It is
usually armed with Maxim guns forward and
rear, and it fires downward through a hole in
the rear fuselage. It is equipped with three
bomb-dropping devices and carries 144 bombs.

In the smaller German armed machines not
already mentioned, are the following: The
"Pfalz" monoplane, equipped with a 100-horse-
power Obei-rusael rotary motor. Its arma-
ment consists of two fixed guns, mounted on
each side of the pilot and firing through the
propeller.

The "Fokker" is also equipped with two
Maxim guns firing through the propellers.

The "Albatross C-3"; the "Aviatik"; the "L.
V. W."; and the "Rumpler" represent the aver-
age type of German biplanes. The size of the
top wing is from 39 to 42 feet, 10 inches; the
bottom wings from 35 to 38 feet ; and the length
from 26 feet 3 inches to 27 feet; thev are all

TEXTBOOK OF MILITARY AERONAUTICS

A view of the French "Spacl" equipped with the Hispano-Suizti 100 h.j). motor and Nickers gun in front and Lewis in the rear.

armed with Maxim guns shooting through the
propellers; some carry Maxim or Parabellum
guns mounted on turrets in the rear. They are
equipped with from two to four bomb-dropping
apparatuses.

In the United States there are, at date of
writing, about a dozen types of twin-motored
aeroplanes, all suitable for arming; but until the
United States entered the war, no steps were
taken to arm the machines with machine guns
or equip them with bomb-dropping devices.

Aeroplane Guns and Cannon

The aeroplane guns and cannon employed
to-day were developed in the year 1912-1914
and perfected, as far as their perfection goes,
during the war. Considered from the stand-
point of the guns of six years ago, the aeroplane
guns of to-day are marvelously efficient.

The most extensively used aeroplane guns
of small caliber are the Lewis and the Vickers
by the Allies, and the Maxim and the Para-
bellum by the Germans. The I>ewis macliine-
^n is an air-cooled, gas-operated, magazine-
fed gun, weighing about 26 pounds with the
jacket, or 18 pounds without the jacket. The
gun is at present used almost entirely without

the jacket, without any loss of efficiency. Its
extreme mobility makes it a most efficient gun
for aeroplane work, being capable of operating
in any position, firing straight up or straight
down, or in any direction. The speed of get-
ting into action and the ability to function auto-
matically in any position are due to the use of
detachable, drum-shaped, rotating magazines,
each magazine holding 47 or 97 cartridges.
^\Tien a magazine is latched on the magazine
post, it temporarily becomes a part of the gun,
requiring no further attention until empty,
when it is snatched off and another snapped on,
as quickly as an empty magazine is dropped out
of an automatic pistol and a loaded one inserted.
Further details of this gun will be given later,
with the detailed description of its construction.
The Vickers is a water-cooled, recoil-oper-
ated, belt-fed machine-gun. Like the Lewis
gun, it is capable of being fired at the rate of 300
to .500 shots per minute, maximum. Its advan-
tage over the Lewis gim is that it is capable of
being fired continuously up to .'jOO shots,
whereas the I^ewis requires changing of maga-
zines after 97 shots. On the other hand, it has
the disadvantage of being belt-fed, so it does not
afford the mobility which the Lewis gun af-
fords. The water-cooling in the Vickers, like

BATTLEPLANES AND AIRCRAFT GUNS

the air-cooling device in the Lewis, has been dis-
pensed with for aerial work, as unnecessary.

Therefore, in most of the French and British
planes one finds the Vickers gun fixedly
mounted in front, and the pilot points the aero-
plane at the enemy, instead of pointing the gun.
The Lewis guns are mounted in the rear or in
front, on mobile or fixed mountings. The Ger-
man Maxim is practically the same as the Vick-
ers gun used by the Allies. The Lewis shoots
.33 ammunition, and the Vickers shoots .30 am-
munition.

The Colt, a gas-operated, air-cooled, belt-fed,
automatic gun, was used as an aeroplane gun in
the beginning of the war, but there are few in
use now. That is also true of the Hotchkiss
and the Benet-Mecier, which is a modification
of the Hotchkiss.

All belt-fed guns are subject to jamming,
particularly when cotton is used instead of linen
webbing, but in the air the one thing to be feared
is jamming, due to the fact of the tremendous
wind-jDressure on the belt. The present method
of mounting Vickers on aeroplanes has prac-
tically solved this problem.

The Fiat aircraft gun used by Italy is in the
order of the Vickers, and shoots 400 shots per
minute.

Large Aeroplane Guns

Details about the larger aeroplane guns have
been kept secret, but there are many in use, there

■M^

WsaM^-S".,

1 reudi isieupoit "Avion de cliasse" flying over a stretch of
"no man's land" in France.

being squadrons of large aeroplanes equipped
with them. A Hotchkiss one pounder, or one-
inch gun, has been used in France and England.
A Vickers pom-pom, or one inch, weighing 180
or 190 pounds, is reported as giving good re-
sults and the Fiat 37 millimeter has been a great
success.

The Davis gun, the invention of Com-
mander Davis of the United States Navy, made
in one-inch and three-inch sizes, is a most re-
markable weapon. The two pounder, six
pounder, and 12 pounder are entirely non-recoil

The French "Corps d'Armee" type, "Letort" battleplane equipped with two ISO h.p. Hispano-Suiza motor.", and mounting two

Lewis and two Vickers guns.

TEXTBOOK OF MILITARY AERONAUTICS

-1

The three motored Italian Caproni biplane equipped with three Frasohini motors.

guns. The two pounder is 10 feet long, weighs
75 pounds, shoots 1.575 projectile with a muz-
zle velocity of 1200 feet per second. The three-
inch Davis weighs 130 pounds. It fires a pro-
jectile weighing between 12 and 13 pounds at
a guaranteed muzzle velocity of 1000 feet per
second, but it has shown a velocity of 1200 feet
in tests.

Another American aeroplane gun is the
Driggs one-pounder, now being manufactured.
It fires one pound shells at the rate of fifty per
minute, weighs one hundred and sixty pounds,
including twenty rounds of ammunition, and
the recoil pull amounts to six hundred pounds.

The Driggs Aeroplane Machine Gun, an-
other new American gim, is similar to the Lewis
gun in that it has a self-contained magazine,
which holds one hundred cartridges, and the gun
is operated by recoil, instead of by gas.

The larger guns, while not so mobile as the
smaller, have greater destructive power and can
reach further than the smaller guns. When
they hit a plane, almost any part of it, they are
almost certain of wrecking it, whereas the bul-
lets of smaller guns are only effective when they
hit the pilot or the vulnerable parts of the aero-
plane.

Problems of Armoring — Vulnerable Parts of
the Aeroplane

So far no progress has been made in the ar-
moring of aeroplanes. To have an effective ar-
mor to protect the pilot and the vulnerable parts

would involve prohibitive weight, which would
cut down the efficiency of the aeroplane beyond
the safety point. The vulnerable parts of the
aeroplane are: (1) the pilot; (2) the gasoline
tank; (3) the propeller ; (4) the motor; (5) the
control wires. Of course, the pilot could be
encased in a steel cabin, but that would limit his
mobility, and the enemy aviator could fly close
and hit the other vulnerable parts of the aero-
plane without interference. The gas-tank and
the motor can be armored to some extent with-
out great additional weight, but when the mat-
ter is considered, it always appears that the

One of the Fokkers hrou^tlit down l>y a French aviator.
This shows the armored liody and the Maxim pni mounted on
top. General fioiiraiid, the late Freneh Conmiandcr-in-Chief
at the Dardanelles, is standing by tlie propeller.

BATTLEPLANES AND AIRCRAFT GUNS

The French Br^guet-Michelin bombing biplane equipped with a 230 Peugeot motor and two guns

weight involved could be invested to better ad-
vantage in adding a gun, thereby increasing the
armament of the aeroplane by one unit.

The proj^eller and the wires cannot, of
course, be armored. Air fighters always aim to
hit the pilot of a machine. The gasoline tank,
the motor, the propeller, and other parts of the
aerojilane get hit as a result of the effort of the
gunner to hit the pilot. Next to the pilot, the
propeller, the gas tank, and the motor are the
vulnerable parts of an aeroplane which get hit
oftener. Only occasional^ are aeroplanes
brought down through the wrecking of the con-
trols or other parts of the aeroplanes. Many
aeroplanes come down at the end of a few hours'
flight with several hundred holes in their planes,
made by bullets from hostile aeroplanes and bits
of shrapnel from the anti-aircraft guns.

Bullets vs. High Explosive Shells

A bullet striking the strut or the rib of an
aeroplane merely leaves a hole, but very rarely

does more damage than that. A shell striking
the same part will wreck the plane. Hence the
shell has its advantages. The mobility of a
larger gun would, of course, be less than the
mobility of the smaller gun, but that is compen-
sated by the destructiveness of the shot.

However, the necessity of having rapid fire
in aerial fighting precludes the possibility of the
larger gun replacing the smaller gun. One
supplements the other. Another thing; it
would not be possible to mount the larger gun
so as to fire through the propeller with the syn-
chronizing device. A shell hitting the pro-
peller would wreck it, and possibly result
in tearing the motor loose, breaking the gaso-
line pipes, and setting the machine on fire.
With the smaller gun, a bullet "hanging
fire" and striking the propeller seldom does
more than make a hole in or splinter the pro-
peller. However, hardly more than one bullet
in 5000 hits the propeller. In firing with the
synchronizing device, it releases a shot at every

TEXTBOOK OF MILITARY AERONAUTICS

four turns of the propeller, permitting the fir-
ing of about 300 shots per minute.

Explosive shells are used with Lewis, Vickers,
Fiat, Parabellum and JNIaxim guns.

Fast vs. Slow Muzzle Velocity

Fast muzzle velocity has certain advantages,
but has the disadvantage of involving greater
weight, due to the necessity of having a stronger
gun to withstand the additional discharge, and
stronger mounting to withstand the greater
recoil.

The same result can be obtained with slow
muzzle velocity by aiming ahead of the target.
In the beginning of the war, there being no
precedent in aerial gunnery, considerable con-
fusion resulted and there was accepted an ex-
tremely high muzzle velocity. Then it was de-
cided that a maximum muzzle velocity of 800
feet per second was sufficient, giving the de-
sired results, but eliminating considerable
weight.

As a general rule, outside of aeronautics a
gun weighs one hundred times the weight of the
projectile. This weight is necessary to give it
the velocity needed to carry the projectile ver-
tically or horizontally over considerable dis-
tances. Shooting down from a height only re-
quires a portion of that muzzle velocity, the pro-
jectile acquiring velocity in its downward tra-
jectory.

A Lewis gun mounted on a French avion cle combat.

Recoil; a Solved Problem

Up to the time of the war, it was feared that
the recoil of a gun would affect the stability of
the aeroplane. Even the recoil of small ma-
chine-guns was feared. It is now a solved
problem for large machines. It has been found

The 1917 type Nieuport avion de rhassc, rqulpjicd with two Lewis guns slioofing over the planes, and a -Vickers gun to slioot
through the pro|)cller. In the rear can be seen a "Spad" and several N'ieuports.

BATTLEPLANES AND AIRCRAFT GUNS

This photograph shows the mounting of
the two Lewis guns on top of tlie plane and
one Vicliers gun in front of the pilot seat
of the single-seater Nieuport biplane.
French official photo, passed by French
censor. {Courtesy of "Flying.")

that aircraft absorb the recoil of any gun of a
size suitable for firing from an aeroplane; that
is, the aeroplane acts as its own recoil cylinder.
This was first discovered in the early part of
1914 when a small naval cannon was mounted
on the first Voisin gun-plane. That fear proved
to be helpful, as it resulted in developing light,
efficient machine-guns and cannon.

Tactics in Air Duels

For the sake of avoiding confusion, it is well
to separate air duels into four classes, as fol-
lows :

(1) Air Duels in Which Participants are
Both Air Fighters Whose Only Func-
tion is to Keep the Sky Clear of
Enemy Machines

The aviator having this mission to perform
usually flies out with a speedy machine
equipped with from one to three aeroplane
guns. He flies as high as he can and remains
high until he sees an enemy machine. Then
he dives down toward it and tries to bring it
down by opening fire on it as he gets to firing
distance, keeping up the stream of fire until he
sees the enemy machine fall. If he missed hit-
ting a vital part, he must either land, if he is

near his own lines, or manoeuver to a point of
vantage to shoot at the enemy again, or try to
rise vertically as quickly as possible, and ma-
ncEuver for a high position again, before the
enemy gets to the point of vantage to open fire
on him.

The first method, that of flying to a height
and then diving down upon the enemy machine,
opening a stream of fire on him, and landing
in case of failure, was originated and adopted
by Immelman and Boelke, the famous German
aviators, who brought down a large number of
Allied aviators before their tactics were known.
But the success of that method is based on fight-
ing enemy machines that are operating over
one's territory and that in itself is basically
faulty, as control of the air means striking the
enemy aviators over the enemy's territory, never
permitting the enemy aviators to come as far
as one's own lines.

A very sound principle of tactics in air duels
is to fly to a height, and then dive down on the
enemy aviator, pouring a rain of bullets on
him. This is, of course, the maneuver that
every aviator would like to perform. Being
above the enemy is an advantage. Unless the
enemy is hit and fluttering away, and needs
only a few more shots to be put hors de
combat, the practice is to make a sharp turn

TEXTBOOK OF MILITARY AERONAUTICS

and quickly climb to a height, and regain a
point of vantage before the enemy can do so.
Having reached a height, the pilot is again at
the point of vantage from which he can shoot
down on the enemy.

In aerial combats, as in naval combats, one's
movements are often changed by the enemy's
movements. The strongest and ablest drives
the other into "tight corners" at sea. But in the
air one can fly over, under, and aroimd the
enemy, and as both combatants are flying at
tremendous speed, which reaches 1.50 miles per
hour in dives, the combatants often fly about
for many minutes before they get to a point
of vantage from which they can shoot at
the pilot, gunner, or vulnerable parts of the
machine.

(2) Air Duels Between Combat Machines

and Armed Photographing, Spotting,

or Bombarding Machines

A duel between a combat machine and an
armed photographing, spotting, or bombing
machine is quite different from the duel between
combat machines. The combat machine will
dive on the armed larger machine, which will re-
ceive it with upward fire from one or more guns.
If the combat machine succeeds in hitting one
of the gunners, it only silences one of the guns,
but still has to deal with the other gunners and
guns. If the aviator does not succeed in hit-
ting one of the gunners, then there is a regular
battery of guns to shoot at him, and he will need

A 37 millimeter gun mounted on a Voisin-Peugeot gun plane.

all the skill that he can command to so ma-
noeuver as to avoid their fire. But while he
may manoeuver swiftly, the enemy machine does
not manoeuver so swiftly ; it is not necessary, for
it depends on driving away the small combat
machine by sheer gun-fire and skill in gun ma-
nipulation. In the first year of the war, when
few machines were armed with aircraft guns
and rifles and pistols were used for aerial com-

A Davis non-recoil jiun mounted
on R British biittleplane. Tlie
three inch pun of this type shoots
a 15 pounder.

BATTLEPLANES AND AIRCRAFT GUNS

A Ilciuy Fariuan

"Lo;pa

dWr

uRc' type, photographed as it was passing another French battleplane, 6,000 feet up.

bats, small, fast German machines attacked the
large, slow, Russian Sykorsky machines and
the Russian gunners were able to bring down
the Germans with their rifle-fire from the plat-
form of the Sykorsky machines.

(3) Air Duels Between Large Armed
Aeroplanes

In air duels between large armed aeroplanes
the tactics are different. These types of ma-
chines, being usually busy with taking photo-
graphs, spotting, or bomb-dropping, seldom go
to great heights; and they are not so well
adapted to diving and swift manoeuvering as the
combat machines. But that is where the na-
ture of the gun and the marksmanship are the
main factor in deciding the victoiy. As most
of these large machines are either twin-motored
or are of the pusher type, with the motor in the
rear, they mount aeroplane guns of large cali-
ber in front, and can shoot at the enemy from
front and sides. The twin-motored aeroplanes
also permit mounting guns in the rear, so that
they can fight from almost any angle of attack.
The employment of aerial gims of large caliber,
and the employment of shells instead of bullets,
brings a new factor of dominant importance in
aerial combat. Whereas a bullet must hit one

of the vulnerable parts of the aeroplane to do
serious damage, a shell will wreck the aeroplane
practically every time it makes a hit.

Formation in Air Fighting

Formation in air fighting is part of the latest
developments in the aerial part of the war.
Fighting in formation began in the early part
of 1916, and by the spring of 1917, in the in-
tensive air fighting that preceded the Allies'
drives, aerial combats had taken place in which
as many as forty aeroplanes participated on
each side.

Since then the ofiicial reports contain many
incidents such as the following, which was dated
June 6, 1917:

"Five hostile formations, all of which consisted
of over thirty machines, were attacked and dis-
persed with heavy casualties. In the course of
the fighting, nine German aeroplanes were
brought down and at least nine others were
driven down, out of control. Six of our aero-
planes are missing."

There are many instances of individual avia-
tors who fought from 4 to 10 enemy aeroplanes
and came out victorious, although not, of course,
bringing down the 10 machines.

TEXTBOOK OF MILITARY AERONAUTICS

Launp Signals for Use of Leaders of
Formations

The code letters are painted on the machine
where visible to the observer and within reach
of the pilot's hand. When the leader wishes
to give an order, he places his finger on the
letter required, which the observ^er then sends
to the machines concerned with the lamp. The
order can be acknowledged by the lamp or by
a "waggle" of the machine if lamps are not car-
ried. Single-seaters working with two-seaters
can take such messages.

The principles of formation defined by the
British General Staff (see chapter on "War-
planes for Bombing and Torpedo-Launching")
are applicable to fighting patrols, as well as to
bombing, reconaissance, and other patrols.
The British General Staff also points out that
in the face of opposition of any strength offen-
sive patrols usually have to fly in formation,
in order to obtain the advantage of mutual sup-
port, but the formation adopted may be gov-
erned solely by the requirements of offensive
fighting. Single-seater scout machines, or even

A \'ickers gun mounted on the "Spad" of a menilier nf the
Lafayette Flying Corps, and the belt with which it is fed.

two-seaters, if superior in speed and chmbing
ability to the great majority of the enemy's
machines, may be able to patrol very success-

Onc of Franre's Short Distance Bombing Machines.

BATTLEPLANES AND AIRCRAFT GUNS

A squadron of German speed bi-
planes of the Albatros type, painted in
variegated colors.

fully alone or in pairs, taking advantage of their
power of manoeuvering and acting largely by
surprise attacks; but in the case of machines
which do not enjoy any marked superiority,
formation-flying is essential. Fighting in the
air, however, even when many machines are in-
volved on each side, tends to resolve itself into

German silver-

ORDINARY ARMOR INCENDIARY EXPLOSIVE
PIERCING TRACING

German ammunition.

3WAY GASOLINE

VAtves

MOTOR SPEED
INDICATOR,

FIXED

hAACHINE-
GON

STARTING
MAGNETO

. MAGAZINE

MAONETO 1 FOR FILLED

SWITCH EMPTY cAnTA.OOt BELT
DCLT

Position of the fixed macliine gun in the
fuselage (as seen by the pilot)

Courtesy of Aerial Age Weekly

a number of more or less independent combats,
and accordingly it has been found advisable to
organize a purely fighting formation.

As far as possible, the groups should be
permanent organizations, in order that the pi-
lots may acquire that mutual confidence and
knowledge of each other's tactics and methods,
which is essential for successful fighting. It
must be impressed on pilots that the group is
the fighting unit, and not the individual.

Normally, a formation shoidd consist of not
more than three groups, and if greater strength
is required separate formations should be em-
ployed, acting independently, but in such a way
as to be mutually supporting.

k,'f^.^J?V^' «*L.-

British aviators figuring out a raid

TEXTBOOK OF MILITARY AERONAUTICS

The DeHaviland Scout Bi-
plane, one of the more recent
British pusher-type scouts.

Ik ^3u

A fighting formation should consist of ma-
chines of one type, but single- and two-seater
machines can be combined for similar perform-
ance. A suitable flying formation with groups
of three machines advances in column groups,
with flank machines echeloned slightly back,
the whole formation being in vertical echelon.
The rear group is the highest, and in the case
of a mixed formation consists of two-seaters,
w^ith machines of equal performance.

Fast single-seaters, if combined with two-
seaters, should fly above them, circling so as to
obtain a good view all aroimd.

In the case of groups of two machines a sim-
ilar flying formation is in line of groups, the
two machines of each group flying one behind
the other, the rear machine at a higher altitude.
The flank groups should not be echeloned back,
as in this position thej' will be unable to use
the center group.

The BritUb Vickers pusher biplane equipped with 100 h.p.
motor. It mounts a gun forward.

Offensive Fighting Tactics

Realizing the fact that fighting tactics vary
with the type of machine, and with the powers
and favorite methods of individual pilots, the
military authorities of the warring counti'ies
have not issued set rules.

Rules of Manoeuver

Individual skill in manoevering favors sur-
prise. A pilot who is thoroughly at home in the
air can place his machine by a steep dive, a
sharp turn, or the like, in an unexpected posi-
tion on the enemj^'s "blind" side, or under his
tail. Individual and collective power of manoeu-
vering is essential if flying in formation is to
be successful, or even possible. It can only be
obtained by constant practice.

The following points must always be borne
in mind:

( 1 ) Pilots and observers must know the fuel
capacity of their machine, and its speed at all
heights.

(2) The direction and strength of
tlie wind must be studied before leav-
ing the ground and during the flight.
This study is most important, since
wind limits the range of action, and
machines, when fighting, are bound to
drift down wind.

(3) To guard against surprise, di-
rection must be varied fretjucntly, un-
less making for a definite i)oint, and a
good lookout must be always kept in
everv direction.

Gnome

BATTLEPLANES AND AIRCRAFT GUNS

''^'^WIJS^.. <■?'/?■":'';"■'', '"^^'^.^f^-'T- ' "

BOMB
RELEASED

The fusclagt' of cine df tlie Gotha biplanes which bombed London. Illustration by courtesy of Illustrated London News.

(4) Every advantage must be taken of the
natural conditions, such as clouds, sun, and
haze, in order to achieve surprise.

(5) The types of host"le aeroplanes must be
carefully studied, so that the performance and
tactics of each, its blind side, and the best way
to attack it, can be worked out. Some machines
have a machine-gun mounted to fire downward

and backward through the bottom of the fuse-
lage.

(6) Height means speed; since it is easier
to overhaul a hostile machine on a dive. If a
hostile machine seeks safety by diving, it is
bound to flatten out eventually and may, there-
fore, be overtaken by a machine from above,
if the latter dives in front of it. The hostile

TEXTBOOK OF MILITARY AERONAUTICS

One of the German Parabellum aeroplane guns.

Three quarter view of tlie Sopwitli biplane.

machine must be watched all the time, in case
it turns.

(7) The engine must be always kept well
in hand in a dive. If it is allowed to choke, the
opportimity will be lost.

Thorough Knowledge of Weapons
is Required

Machine-guns in the air, as on the ground,
are very powerful weapons of offense, owing
to the volume of fire they are capable of pro-

An aerotlnmie just back of a line of trenches In France photof;ru))lietl from an aeroplane. A twin-motored ("luidron and some
SupwiUiK are shown on the ground. The motor transports arc in the court-lilie place. (French official plioto.)

BATTLEPLANES AND AIRCRAFT GUNS

«1

A French type of biplane used for aerial photography and to direct artillery fire, showing the gun mounting
at the rear seat. (Photo Committee on Public Information.)

UWIS AUTOMATIC MACHINC GUN
• .. jnODCiLi ISIS ...

Section diagrams ot the Lewis Automatic Machine Gun. The gun is an air-cooled gas-operated, magazine-fed arm, weighing
26 pounds. Its speed and ability to function automatically in any position are due to the use of detachable drum-shape rotating
magazines holding from 47 to 97 cartridges. It may be used with tripods or mountings of any design. The Lewis gun has
shown adversility and sureness of action which makes it equally effective on rigid bases or the undulating, fragil supports in

the air.

TEXTBOOK OF MILITARY AERONAUTICS

ducing. Their effective use in the air demands
even more skill and practice than on the ground.
It is dependent on:

(1) Absokite famiharity with the mechan-
ism of the gun, so that the jamming can be
rectified in the air.

(2) A high degree of skill in manipulation
and accuracy in aim, both on the ground and in
flight.

(3) Constant study of the conditions affect-
ing their use in an aeroplane, and continual
practice under these conditions.

Memoranda:

CHAPTER V

THE FUNDAMENTAL PRINCIPLES OF AERIAL COMBAT

By Oscar Ribel
Chief Instructor in One of the French Military Flying Schools
Translation by Augustus Post

The fifth arm has taken a very important
part in the European war. The warmest ad-
vocates of mihtary aviation in times of peace
never dreamed of the vital importance of the
aeroplane to-day.

In 1907 the most remarkable aerial flights
were no farther than 1 kilometer, or %ths of a
mile, at a height of 30 meters, about 100 feet.
The marvelous accomplishments in aviation
during the last ten j^ears are astounding. The
most optimistic prophecies did not anticipate
one half the actual reality. Who dared to be-
heve, when Farman timidly tried his wings at
Issy-les-JNIoulineaux, that nine years later es-
cadrilles of thirty or forty aerial warriors would
sail off into space to engage in heroic aerial
combat against each other.

Aerial fighting has given an opportunity to
develop in both the French and English rare
qualities of courage, coolness, and hardihood.
The Germans, on the other hand, are less well
trained and equipped than their adversaries but,
as is frequently recorded, exhibit undeniable
bravery. The system used in aerial fighting
differs in the German and Allied forces. In
France we have distinct types of aeroplanes for
different purposes, that is to say, for recon-
noitering, "spotting" or directing artillery fire,
and for carrying bombs. All these aeroplanes
are protected by an escort of machines espe-
cially adapted for speed and fighting, and they
are well armed. The Germans use their ma-
chines more indiscriminately for these various
military operations. They do not have so
many types of machines, and thus those they
have are capable of being used for different

purposes with equal efficiency. An exception
to this statement are the Fokkers and the Wal-
vets, which are flown by their most expert avi-
ators and are used exclusively for fighting the
enemj'.

From a technical point of view French avia-
tion is about the same as German, but our pilots
are superior scientifically to the Germans, and
the number of cur "aces" is constantly increas-
ing. Practically all of them fly the Nieuport
or Spad, and their victories up to date can be
numbered by the himdred. Naturally we can-
not describe the methods employed by each one

Fig. 1 — The "Loop" as an aerial military manoeuver. At-
tacked by four or five German machines, a French biplane
turned completely over and returned by means of "looping the
loop" to attack the squadron which was attacking him in the
rear.

of these "aces" in fighting the enemy, because
almost every one depends upon the marvelous
individual skill with which they perform their
acrobatic feats. One example among thou-

TEXTBOOK OF MILITARY AERONAUTICS

sands may be quoted. It is well known among
escadrilles at the front and will give an idea of
how every pilot must cut the "Gordian Knot."
In the course of a reconnoitering flight in the
East, sub-Lieut. Navarre found himself sur-
rounded by five or six German machines.
Three or four were above him and the others

t
I

ill

ZOOmetres,

Fig. 2 — The favorite attack of the Walvets. Walvets patrol
two by two. A 200 meters above and 200 meters behind B. If
a machine C is encountered B engages in combat with it while
A remains to survey the zone of battle to prevent surprise on
the part of another machine which might come up to render
assistance.

were below or at the sides, which prevented him
from going to the right or to the left, either
in rising or descending. It seemed impossible
for him to escape. Without losing for an in-
stant his remarkable coolness, our valiant "ace"
surprised his adversaries by making a complete
loop over the entire group of assailants, and
following up the nearest machines, discharged
an entire belt of cartridges from his machine
gun and brought down two machines one after
the other. The other pilots retreated as fast
as possible to their lines, pursued by the in-
trepid Navarre.

The German "aces" are much less numerous
than our own, the best among them being Cap-
tain Boelke, who died the 28th of October, 1916,
after having brought down his fortieth adver-
sary.

We count as victories for our pilots only the
enemy machines which fall inside our lines, or
fall in flames in unoccupied territory', but the
Germans do not hesitate to count every machine

which is brought down for one cause or another,
and is thus obliged to abandon the fight. If
we adopted the same method of counting, it
is certain that Guynemer, among others, has
brought down more than sixty enemy machines.

French aviators often fight twenty or thirty
kilometers behind the German front. A Ger-
man reconnoitering party must be checked in
its operations and brought down if possible.
During the course of our ofi'ensive on the
Somme and at Verdun, our machines estab-
lished a veritable barrier across our front,
through which no German aviator was able to
penetrate; and this lasted for several days.

Speed and climbing ability are essential for
a fighting machine, as the aviator has to outfly
his adversary and strike him in a vital spot at
an opportune moment. The Fokkers, the
Walvets, and the L.V.G. are the principle
types used for reconnoitering over the front,
and have a speed of 1.50 kilometers per hour
(about 100 miles). They climb very rapidly,
and the altitiade at which aerial combat is gen-
erally fought is about 4000 meters (14,000
feet).

Generally speaking, the German fighting
pilots, especially those who fly the Walvets,
employ the following tactics when they come
over our lines and engage our aviators. They
always go in groups composed of units of two
machines each. If an enemy machine is en-
gaged by one of these units, the first of the Ger-
man aviators begins the battle and the second
man remains about two hundred meters above,
his mission being to overlook the zone of combat
without interfering directly with the fighting.
If a second adversary comes to the rescue, how-
ever, it is his turn to attack and drive away
the rescuer, while if his partner is vanquished,
he returns to his lines as quickly as possible.
Often the manoeuvers are more involved, and
the aviators fly in large squadrons for mutual
protection. If an isolated enemy is encoun-
tered, he is quickly surrounded and must seek
safety in the speed of his flight.

The speed of the fighting machines is great,
and there is danger therefore of breaking the
wings. A machine which flys at 180 kilometers
an hour (about 110 miles), rises two thousand

FUNDAMENTAL PRINCIPLES OF AERIAL COMBAT

meters in seven minutes (about 7000 feet), and
dives almost vertically from this height, ex-
periences a tremendous strain which, in time,
is apt to cause weakness. Fighting machines
have to perform extraordinary feats in pur-
suing the enemy. They dive vertically, and if
the wings break under the jiressure caused by
these conditions, the machine at once falls.
German machines, generally speaking, have a
good factor of safety in their different parts.
Many accidents have been caused after a ma-
chine has had many repairs, or through some

Fig. 3 — The "Dive Attack." To train the machine gun upon
its target below the machine must be pointed down at least 60
degrees.

hidden fault of constniction. Recently at the
front near Verdun an aviator was pursuing a
German machine and, in his turn, was pursued
by a small Rumpler biplane. At the moment
when the French pilot, after bringing down his
first adversary, was preparing to face this new
assailant, the Rumpler dived straight toward
the earth in a sudden bold dash. The wings
broke and folded up above the fuselage. Many
Rumpler machines have met the same fate in
other air battles. The constructors thus invol-

untarily contribute to the success of our pilots,
and thereby deserve our thanks.

The German "aces" generally fight in con-
junction with a squadron of accompanying ma-
chines. These are charged with the duty of
occupying the attention of the enemy until an
opportune moment for attack. Boelke adopted
the following tactics, as described by M.
Jacques Mortane. The German flew with an
escadrille of five or six good pilots on Rolands,
Walvets, or Fokkers; he preferred a Fokker,
but sometimes was seen on a Roland, or a small
Aviatik. As soon as the well-known profile
of an Allied machine was seen on the horizon,
the squadron rose to engage it. The duty of
Boelke's support was to surround the enemy
and block his path. They would fire from all
sides, suddenly ceasing the instant Boelke made
his entrance upon the scene. The latter would
dash at his prey and attack furiously, firing a
thousand cartridges from his machine gun.
Boelke followed up the fight, in contrast to the

Fig. 4 — The tactics of the famous Boelke. The duty of the
machines C, D, E, is to surround their adversary B at a given
moment. A, who has been hidden from the view of his adversary,
dashes at him, firing his machine gun furiously.

custom of many of his compatriots. These
rarely continued an engagement with an ad-
versary who was not brought down at the first
shot. Such was the method adopted by Lieut.
Immelmann, one of the best of the German
aviators. He would dash up to an enemy's

TEXTBOOK OF MILITARY AERONAUTICS

machine, and when so close that a collision
seemed imminent, would discharge his machine
gun at it as he passed by. Once out of range
he would not return to the attack, but would
fly away, which cannot be considered very
heroic.

The Germans usually fly very high. When
they see French machines they hesitate to cross
our lines, which are always well guarded by our
fighting machines, especially during the periods
of Allied drives. The weather plays an im-
portant role in air fighting. Calm days, when
the sky is full of dark, gray clouds, are the
most favorable for surprise attacks. The
clouds act as a screen and allow the aviator to
hide until the last moment, before he makes a
dash at an unsuspecting enemy.

The Germans are ■ well versed in one trick
which they invented and which they have often
used. When the bank of clouds is thick, one
of their machines flies down to an altitude of
two or three hundred feet. This machine may
be of any class, but it is usually a slow machine
of an old type, and not heavily armed.

Fig. 5 — The Tactics of IiiiiiicliiKin. The iiiiuliino A daslies
straiglit at its enemy B, firing at him furiously. If he failed to
bring down his prey he fled and did not return to the charge.

It appears to be relatively easy prey, and is
quickly discovered by the French machines.
They give chase, not hesitating to follow it,

even to some distance behind the German lines.
At the moment when the French pilot finds
conditions most favorable to begin his attack,
three or four German fighting machines of the
latest and most formidable model appear.
Flj'ing above the clouds, they have been follow-
ing the two antagonists while hidden from view,
and never appear until the enemy is at least
twenty or thirty kilometers from his base. The
number of attacking machines, and the difficul-
ties in getting help in time, make it an extremely
precarious predicament for the French avia-
tor.

An air battle does not necessarily end by
the complete destruction of an enemy machine,
or the killing or disabling of a pilot. A case
has occurred where a German aviator was at-
tacked by a French "ace." The German was
convinced that he had no chance, lost his nerve,
and preferred to come down in safety to having
his body riddled with bullets. He directed the
observer with him to throw up his hands, while
he steered his captured machine, and following
his vanquisher to the nearest aviation field,
landed by the side of his captor. In this way
Lieut. Laffon gathered out of a clear sky a
Fokker of the latest model, and brought it to
the aviation center of Plessis-Belleville. The
feat was all the more remarkable and creditable
to the officer because he had no arms aboard,
except a revolver.

Before the war the question of arming ma-
chines received only superficial study, at least
in France. At the beginning of hostilities only
a few aeroplanes were equipped with machine
guns. ]Many of the aviators had only a rifle
with which to defend themselves against attack.
To-day, as the enemy well knows, our machines
are very efficiently armed for both attack and
defense. The position of a machine gun on the
aeroplane plays a great part in the success of
air fighting. We know that the Germans have
studied the problem with great care, and their
machine guns are mounted in one of the five
following positions:

(1) Above the upper plane (machine guns
stationarjs firing through the propeller).

(2) Along the fuselage (gun stationary,
shooting through the propeller).

FUNDAMENTAL PRINCIPLES OF AERIAL COMBAT

(3) In rear of the lower plane (guns mova-
ble in a revolving turret) .

(4) In front of the cockpit (gun movable
and able to fire in all directions ; single-motored
machine with a pusher propeller).

(5) Both in front and in rear of the cockpit
(gun movable; twin-motored machine, tractor
propellers, with a central cockpit).

The first arrangement has been adopted by
several manufacturers of small speedy bi-planes
in Germany, and is similar in almost all points
to the system used on our Nieuports. The ma-
chine gun is stationary on the upper plane, par-
allel with the fuselage, and is controlled by a
"Bowden" flexible wire control fastened to a
rod beside the pilot. To train the gun upon
its mark in the vertical plane one must point
the aeroplane up or down; and to aim in the
longitudinal plane, the aeroplane must be
pointed in the direction of fire, since the gun
is firmly mounted on the axis of the nlachine.
When the aeroplane attacked is just below the
pursuing machine, the latter must dive verti-
cally and attack its adversary while inclined at
ninety degrees, in order to bring the machine
gun into range. In practice, the angle of at-
tack is not quite as steep as this, for the attacked
machine is not exactly beneath its adversary's
gun. It is at least 100 meters (300 feet) away,
and when the attacking machine opens fire, it

angle. The difficulty of hitting the mark is
great, since the gunner and his object are mov-
ing rapidly, and the movements in steering an
aeroplane are complex and relatively slow.
The mounting of the gun on the upper plane
is best adapted to the machine which has the

Mitrailleuse fine

-Mitrailleuse mobile
a tourelle

Fig. 6 — Mounting of the two machine guns on the new bi-
plane L. G. V. The machine gun in front shoots through the
propeller and is fired by the pilot. The rear gun mounted in a
revolving turret is fired by the observer.

is at an angle of 55 or 65 degrees. This, when
compared with the horizontal, is a considerable

Fig. 7 — Arrangement of a machine gun with a limited field
of fire. The gun is mounted in front of the car on an elevated
support. The field is limited by the extremities of the aero-
plane.

pilot's seat behind the wings. Consequently,
to gain the best chance to reach the aviator him-
self, his adversary must strive to attack from
above.

The mounting of guns for firing through the
propeller was first attempted by Roland Gar-
ros, who was taken prisoner before he was able
to destroy his machine. The Germans were
quick to copy this method of mounting guns,
and have made many improvements, as it was
well adapted to the Fokker machine and gave
very good results. On the Fokkers, the gun is
mounted stationary above the hood, a little to
the right of the axis, on a level with the head of
the pilot. The propeller causes only slight in-
convenience, but on account of the gun being
firmly fixed, the entire machine must be aimed,
with the attendant difficulties already men-
tioned. It is also possible to shoot through the
propeller by using an automatic device to
momentarily stop the fire during the passage
of the propeller-blade in front of the gun. The
latter is mounted directly behind the propeller.
In this device the motor is connected with the
machine gun, and a cam controls a mechanism

TEXTBOOK OF MILITARY AERONAUTICS

which stops the fire for /^oo of a second, while
the blades of the propeller are in the path of
the bullets. When the propeller has passed,
the gun is free to fire again. If a pilot wishes
to shoot, he presses a small lever placed on
the steering post, which is connected to the
trigger of the gun.

The company licensed to make the Nieuports

Fig. 8 — Vertical field of a machine gun mounted on a pivot.
In the vertical plane the fire is very extended. It is only lim-
ited by the parts of the aeroplane.

in Italy recently invented a device which en-
ables one to shoot through the propeller, prac-
tically identical with that used on the Fokker.
It is based on the difference between the speed
of the gun and the speed of the propeller ; that
is to say, the ratio between the bullet and the
propeller-blade is 700 to 160. This difference
is used to regulate the stopping of the machine
gun during the passage of the blade of the pro-
peller in front of the barrel of the gun.

The arrangement which Garros used was ex-
tremely crude. It consisted simply of a small
piece of steel, hard enough to resist a bullet,
placed on each blade of the propeller opposite
the barrel of the gun. If a bullet chanced to
hit the propeller, the metal deflected it without
causing damage to the propeller-blade.

The German bi-planes, like the Ij. V. G., for
example, have two machine gims. One is sta-
tionary on the upper plane, the other movable

and mounted on the fuselage behind the observ-
er's seat, on a revolving turret. This gives it a
great range of fire. The turret is a ring of
wood which turns freely around the cock-pit
on ball-bearings, with a bracket arm which holds
the gun and permits it both to be trained in
the vertical plane and swung around in the hori-
zontal plane to either side of the fuselage, so as
to point in any direction. Two small clamps
hold the turret and gun firmly in any position.
This arrangement gives a wide range or fire to-
ward the rear in all directions, and on either
side, both above and below. It is even possible
to fire ahead, above the wings of the machine.
The rear machine gun is often replaced by a
"fusil mitrailleuse," or automatic rifle. To pro-
tect the blank sector of this gun arrangement,
the fuselage is provided with a tube-like open-
ing, inclined at an angle of forty-five degrees.
This tube allows the gunner to see and fire
through the fuselage at the enemy, if he tries to
hide from view of the gunner below the rear of
the machine.

The machine guns, when mounted in front
and rear, are both fired by the observer, but in a
recent type the forward gim was placed be-
tween the two planes beside the motor and
parallel to it, being fired by the pilot.

At the beginning of the war some German
machines had a cockpit, like the French Far-
mans, with a gun mounted on an elevated sup-
port. This mounting left a large blank sector
of fire, and was afterward abandoned. The
gun did not have much sweep, and its zone of
fire was restricted by passengers, wings, pro-
peller, cables, struts, etc. This was remedied
in a measure by mounting it on a turret, which
allowed it to fire in all directions, but not at all
angles. This type of machine is not used to-
day at the front. It has been replaced by the
A. G. O., which is provided with two motors and
tractor propellers, and a central car armed with
two machine-gun turrets. One machine gun is
placed forward, sweeping the horizon for 180
degrees and the other is in the rear, its range
also controlling 180 degrees of the horizon.
Between them the entire horizon is covered.
All of the German machines are armed with one
or two Maxims, Lewis, or Parabcllum machine

FUNDAMENTAL PRINCIPLES OF AERIAL COMBAT

guns. Some aeroplanes have three machine
guns, and these are considered the best for ac-
tual service. The Parabellum has a belt of
cartridges which contains not less than a thou-
sand projectiles.

If each pilot has his own method of fighting,
each type of machine has its weak points; and
these points must be well known, in order to
make a successful attack upon it. When at-
tacking a machine it is necessary to learn how
its guns are mounted, in order to know whether
to attack it from above, below, or from the side.
If the field of fire of the machine gun has cer-
tain dead points, it is thereby handicapped, and
may be attacked to advantage. A pilot who is
attacked by an Aviatik is exposed to fire from
all directions, except in the zone in front of the
propeller. In the case of ordinary Aviatiks,
with the gunner in front, the machine gun can
be placed at will on the right or left side of the
fuselage. It is placed upon a pivot mounted
on a carriage. This carriage can be moved on
two guides, or slide bars, that run along the
fuselage to a convenient point for firing. A
clamp holds the carriage at any spot, so that
one can fire in all directions. An aviator who
attacks an L. V. G. which, as we have explained,
has two machine guns, must decide whether it
is better to stay in front or in the rear of the

line of fire between the forward and the rear
gun.

Thus we see that the identification of the type
of enemy aeroplane is absolutely necessary for

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Propufaeur 'j

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1 ^J..J-— — — r

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Fig. 9 — Mounting of two machine guns in a bi-motored ma-
chine. The arcs of fire in the horizontal plane meet each other
when the guns are mounted in this manner.

an air warrior. Unfortunately, the diversity of
types of machines employed by the Germans,
and the frequent changes made in service, ren-
ders this identification extremely difficult.

German positions reduced
by Frencli artillery through
the directions given by aero
observers. The center pho-
tograph shows the trenches
and German position in
broad perspective. The im-
portant positions are shown
by numbers and are shown
in detail in the smaller pho-
tographs. The aero observ-
ers directed the artillery
fire on these positions.

Photograph No. 1 shows the
effects of the French shells
on a typical one of many
German points d'appui. No. 2
shows the condition in which
the captured German trenches
were found. No. 3 shows the
remains of the emplacement of
a German battery. No. 4
shows the ruins of a small l)ut
very strong German fortified
post. No. 6 shows the result
of the French bombardment on
the German defensive line be-
fore the River Suiiipe. No. (!,
like No. 2, is another typical
scene in the captured Germnn
trenches, showing their general
appearance after the bombard-
ment. No. 7 shows all that re-
ma ine<l of some of the deepest
German dug-outs and trench
shelters. No. 8 illustrates the
demolishing effect of the French
artillery fire on the solid con-
crete structures built by the
Gennans in their trenches.

An aero observer flying over the German lines in a Farman biplane. The shrapnel is bursting around him.

CHAPTER VI

DIRECTING ARTILLERY FIRE BY NIGHT AND DAY SIGNALING TO

AND FROM AIRCRAFT

Aircraft are the necessary adjunct of coast
and field artillery, and the aero observer is the
man behind the man behind the gun. Thou-
sands of American aero observers will have to
be trained, therefore the information is given as
complete as possible, so that prospective observ-
ers may familiarize themselves with the funda-
mental principles.

Aeroplanes and captive balloons are used for
spotting artillery fire.

The observers have to perform two functions,
mainly as follows :

(1) To locate the target, which may consist
of hostile batteries, bodies of troops, advanced
trenches, trains and mechanical transports
bringing supplies or reinforcements to the
enemy, temporary headquarters, or strategic
positions held by the enemy.

(2) Having discovered the target, the ob-
server directs his battery to open fire, and then
notifies the gunners of the effect of the fire by
wireless, if from an aeroplane, and telephone
from a kite-balloon.

Practice makes it possible for the aviator and
the gunners to reach such a thorough under-
standing that the observer need not send more
than brief wireless signals, such as "short,"
"long," "right," "left." Likewise the gunner
seldom has to fire more than three shots before
hitting the target.

The observer must know something about
artillery, such as the fact that field guns are
used for barrage fire and howitzers for counter
battery destruction.

Wliile looking for the target the aviator may
have to fly down low. As soon as he has found
the target he flies to whatever height is neces-
sary to avoid crossing the trajector of the shells.

The aviators cooperating with the artillery are
usually located at an aerodrome located from
ten to fifteen miles behind the firing Enes, and
are instructed to be over a given place at a cer-
tain hour to spot the firing. At the time desig-
nated the aviators hover over the batteries and
watch the results of the firing.

From a height of 4500 to 6000 feet the ob-

TEXTBOOK OF MILITARY AERONAUTICS

servers can usually see clearly the effect of firing
of large caliber guns, but the firing of three-inch
guns is very hard to detect.

Well-trained observers are necessary for
spotting, as it is easy to confuse the puffs of
smoke of the hostile anti-aircraft guns with the
puffs of smoke of the shooting of one's bat-
teries. The fact that the enemy's anti-aircraft
guns keep up a sustained fire against the avia-
tor, and that hostile aei'oplanes may be lurking
in the sky ready to plunge down on the unsus-
pecting artillery observer, turning on him a rain
of bullets from two or more Lewis or Vickers
guns, prevents the observer from giving all his
attention to watching the result of the fire of his
batteries.

The observer often sees what appears to be a
hit on the part of his battery, but which is,
in reality, an anti-aircraft gun shooting at
him.

While spotting artillery fire the aeroplanes
usually fly in figures 8s and circles, changing

their direction as often as possible, so as not to
allow the men behind the anti-aircraft guns the
chance of anticipating what direction they will
fly next — because in such a case the anti-air-
craft guns would be turned effectively on the
aeroplanes.

While the work of spotting artillery fire re-
quires all the faculties that the aviator and ob-
server possess, it is not more dangerous than
bombing or aerial fighting. For one thing, the
machine is usually in flying distance of its own
aerodrome, where it can land in case of being
badly hit.

This last remark must be qualified, because
aeroplanes engaged in spotting artillery fire are
always hit by bullets or pieces of shrapnel.

The danger from the aeroplane catching fire
is also minimized somewhat by the fact that the
aviator is in flying distance of the aerodrome,
although the only safe protection from fire is:

(1) To use aeroplanes the wings of which
are varnished with an inflammable dope.

Directing ortlllrry Arc over the inountalnii. Monte Pasubio, on the Trentlno front, as seen from a Capronl macliiiii'.

DIRECTING ARTILERY FIRE

(2) To always have a fire extinguisher at
hand.

(3) Every machine of this type should have
an arrangement which permits the aviator, as
soon as he is within gliding distance of a landing
field, or sooner if necessary, to open a valve and
let out all the gasoline and oil.

Some remarkable records have been made by
aviators and observers engaged in spotting
artillery fire. Among them is the record
of the French lieutenant, Perrin de Bricham-
baut, who has been engaged in this work since
the beginning of the war and in less than two
years flew over the enemy lines eleven hun-
dred hours. The record for one day was seven
hours of continuous flying over the enemy
lines !

Spotting artillery fire at night is more diffi-
cult in a way, but less dangerous — provided the
aviator has had experience in night-flying. The
targets are detected by the lights, since the
enemy cannot operate unless it has lights, and
even the smallest liglit is seen from the air.
The flash of guns being fired supphes the di-
rections to the enemy batteries. At night both
the wireless and the Very pistols are used for
signaling.

An artillery observer flying a Caudron biplane over the German
lines, photographed from another aeroplane.

Methods and Codes Used for Communi-
cating From and To Aircraft

The methods and codes used in communi-
cating from and to aeroplanes change continu-
ously, as each side quickly learns the enemy's
methods and codes and any improvements
made. But there are basic principles which

A few F.E.2.B machines of the Royal Flying Corps, used for directing artillery fire, ready for a flight. (British official photo.)

TEXTBOOK OF MILITARY AERONAUTICS

The observer in a £a|itivc balloon directing artillery fire.
His equipment includes a chart of the sector, divided in squares,
which enables him to quickly estimate the accuracy of the fir-
ing. He transmits the information to the battery commander
who, in turn, orders the gunners to fire according to the in-
formation received from the observer.

vary only in detail and which every student
should leam.

The pilot, the obsen^er, or both remain close

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to the commander, or they are notified to be fly-
ing over a certain spot at a certain hour.

An aeroplane may serve from one to four
batteries. When the battery commander
wishes to use the aeroplane to locate a target, he
explains what he requires and, if possible, the
nature of the target and its general direction.
The aeroplane then rises to the necessary height
behind the battery, in order to run less danger
of injuiy by hostile fire. Meanwhile, strips of
white cloth are laid out on the ground near the
batteiy, so as to give the supposed direction of
the target and other instructions. The aero-
plane, having reached the required height, flies
out over the battery to find the exact position
of the target.

The Observer's Special Map

When more accurate definition is wanted the
same method is used, but the sides are divided
into 100 parts and four figures are used instead
of two. Thus 0843 denotes 08 parts East and
43 parts North of origin.

These maps contain as much information as
is available regarding the enemy position, the
apparent importance of enemy's trenches, en-
tanglements or other obstacles, fortified and
unfortified mine craters, ditches, railways, etc.

There are also shown in different ways, first,
second, and third class roads, whether fenced or
unfenced; double- and single-track railways,
footpaths, car tracks, buildings, conspicuous
points, elevations (which are given in meters),
etc.

Rrrrlving mcMagrfi frmn tni- mito nlisrrvrr, and transmitting
thrm fo the gunnerx.

A French gun of large calibre being fir

DIRECTING ARTILLERY FIRE

A captive balloon observins; and directing artillery fire somewhere in France at dawn.

There are also shown the location of trenches
and other prominent positions of the observer's
own forces, as it is necessary that he know these.
While it is true that if the enemy captures one
of these maps he obtains information regarding
positions, it is also true that the enemy usually
already has that information, since no such
supremacy has as yet been obtained as to pre-
vent an occasional aeroplane from taking photo-
graphs or observing — if only from the enemy's
lines, with the support of the anti-aircraft gvms.

Signaling With Very's Lights

When radio fails, Very's lights are used. In
this case the observing aircraft should remain

close to their own guns, at the best height for
observation, in order to facilitate communica-
tion. In some cases, however, it may be neces-
sary to fly out further toward, or even over,
the target in order to insure accurate observa-
tion. In such cases much delaj' will ensue if
the aeroplane has to come back over its own
guns to signal the results; on the other hand,
if it remains out in the front, the signals may
not be seen.

The observer having located the position of
the target and conveyed the information to the
artillery commander, receives from him the sig-
nal "Observe for line."

The aeroplane now moves, keeping on that

TEXTBOOK OF MILITARY AERONAUTICS

An officer of the British Royal Xavy Air Service shooting a
Very pistol, used for signaling from the aeroplane to the ground
and between aircraft.

side of the battery farthest from the sun, so
that the signals can be easily seen.

Rounds can only be seen with ease when the
aeroplane is moving out toward the target. If
the distance A to B is about one mile, two
rounds can be observed during each outward
flight. As soon as the line is obtained the sig-
nal "Observe for range" is sent. The aeroplane
now moves in an elongated figure of eight, al-
ways turning toward the target. It will keep

behind or in front of the battery, according to
the position of the sun.

Range having been obtained, the signal "Ob-
serve for fuze" is sent, etc.

When the signal "Land" is sent, the aero-
plane comes down at a place previously selected
and not necessarily at the spot whence the sig-
nals are sent.

Two men should be detailed from the battery
to watch the observing aeroplane, one with field-
glasses looking for the signals, the other with
his naked eye keeping a continuous watch on it,
so as to make certain that no mistake is made
as to the actual machine, since, when there are
several aircraft out in observation, confusion
between them is very likely to arise.

With Very's lights the following code of sig-
nals may be used for communication to the
ground.

Kite-Balloons for Spotting Artillery Fire

Kite-balloons are used extensively for spot-
tiiig artillery fire. The kite-balloons are usually
located a few miles behind the lines and the
balloons are sent up to a height of about two
thousand feet, from which the observers have a
bi'oad perspective. For close-range observing
the kite-balloon observer can do more accurate
work than the aeroplane observer. That is also
true about observing at night. The kite-bal-

U. S. Army Aeroplane
Xo. SO of the North Is-
land aviation school
which was one of the
aeroplanes which was
cquipjied by Capt. C. C.
Culver for radio work,
the aerial wires being
shown above the upper
plane in the picture.
I.ieut. Herbert Dargue,
I'. S. A., is seen at the
])ilot's wheel, while Major
Frank P. I.nhm is in the
observer's seat. The of-
ficers had just completed
a flight.

DIRECTING ARTILERY FIRE

Rigging up the -wireless receiving post be-
tween two wireless' motor truclts "somewhere
in France."

loon observer, having knowledge of his own
position, can easily figure out the location
of any light which he may see, or of the flashes
of hostile guns. The kite-balloon observer
transmits the information by telephone to the
officer below, who transmits it to the battery.

The Dubilier-GoU Semi-Radio Telephone
System for Captive Balloons

Communicating from an observer's balloon
to the battery commander is usually done by
means of the regular standard telephone instru-
ments operated by a few dry cells, using two
wires, the same as with the ordinary house tele-
phone. The holding cable of the balloon,
which is used for hauling the balloon up and
down, is especially constructed in such a way
that it has a small insulated wire in the center,
which is used for the return circuit. This in-
sulated wire makes the cable not only expensive,
but weak in construction, especially when over
2000 feet are used, when the strain on the cable
can be seen from the height of 3000 ft., and a
prearranged code of signals can be made by
this means.

Very's lights fired from the ground can be
seen from aircraft with the same ease as those
fired from the air can be seen from the ground,
if the observer knows exactly where to look for
them.

Signaling between Aircraft

It is possible to signal between airships with
a signal flag by semaphore or ISIorse code, pro-

vided the aircraft are broadside to each other,
and not over 1000 yards apart.

Between aeroplanes, Very's lights can be
used in accordance with a prearranged code.

Major C. C. Culver, U. S. Army, who has
done much important pioneer work in radio so
applied to aeronautics, and is mainly responsible
for placing the United States foremost in this
science, has evolved a method which permits
intercommunication between aircraft in flight by
wireless telephone.

Cooperation between Balloons and Artillery

By Major D. RAINSFORD HANNAY
British Royal Flying Corps

Courtesy of "Aerial Age Weekly"

It is a very well-known axiom in war that
the closest co-operation between the various
arms is necessary to secure the best residts ; and,
when it comes to the question of captive bal-
loons observing for artillery, the more that each
imit knows about the methods of, and the diffi-
culties experienced by, the other the better.

I propose, therefore, to describe the working
of a balloon section of the British Army in the
field.

As regards organization, the balloon service
of the Royal Flying Corps is divided into wings,
companies, and sections. A section consists of
four officers and 90 men and works one bal-
loon. A company consists of two sections. A
wing consists of all the companies in any one
army.

The balloon now in use in the field is a stream-

TEXTBOOK OF MILITARY AERONAUTICS

line balloon, the invention of Captain Caquot,
of the French Army. It has a cubic capacity
of 950 cubic meters and is capable of lifting two
observers to a height of 4000 feet. Each sec-
tion is provided with a mobile winch, the engine
of the winch being quite separate from the en-
gine of the truck on which the winch is mounted.
Theoretically, the balloon should be let up from

the ground at a considerable distance behind
the lines and then run forward on the winch
with the balloon high up in the air; but, in
practice, it is found that there are very few
roads left near the lines which are fit for a heavy
truck, and, even if one is found, it is probably
too congested with traffic. Owing to these rea-
sons, the majority of balloons, in France, are
stationary, at an average distance of about 6000
yards behind the line. Where sections have
been able to move their winches forward, they
have got within 4000 yards of the front line.
As regards observation of fire, the work of

the balloon observer is chiefly with the heavier
pieces of artillery, such as the

6-inch howitzers and the 4.7-inch guns,

8-inch howitzers and the 60pounder guns,

9.2-inch howitzers and the 6-inch guns,

12-inch howitzers, '

15-inch howitzers.

In the earlier days of the war, when there
were fewer heavy batteries, balloons used to ob-
serve for Field Artillery, but, owing to the
great increase of the howitzer batteries, and,
also, to the somewhat altered role of the Field
Artillery, very little work is done with them
nowadays. In order to avoid confusion. Field
Artillery in the British Army consists of only
18-pounder guns and 4.5-inch howitzers.

The balloon section is connected by telephone
to all the batteries with which it is likely to
work. The sketch gives a typical communica-
tion scheme of a section in the field. The up-
keep of the telephone service is most important,
and it is necessary that batteries should give
as much mutual assistance as possible. Unless
the lines are working well, the balloon might
as well be on the ground, for all the good it
can do. An advantage which a balloon has over
an aeroplane, and one that compensates for a
great many of the disadvantages, is the fact that
the observer in the basket can talk direct by
telephone to the batterj' commander on the
ground, and does not have to confine himself
to a limited code as used on the wireless. To
refer to the sketch, all the telephone lines,
shown, with the exception of those to Corps
Heavy Artillery Headquarters, are the shoot-
ing lines of the section, and are used only when
observing for, or when arranging shoots with,
batteries. Lines lead from the balloon camp
exchange to an advanced exchange which is
placed in a central position among the batteries.
Now when the balloon is in the air, it is con-
nected by a telephone cable to the winch, which
is, in turn, connected by aerial line to the camp
exchange, and, tapped in one this line, is the
chart room of the section, where all the map
work and the arranging of shoots with batteries
are done.

I have purposely enlarged on the commnni-

DIRECTING ARTILLERY FIRE

• , ' •\ •• - ■•■'••.■•'."•. ... ■

.\ AREA IN 'PLAr^E OF PURSUER^ - . -

.• ■ . PrtOPEI-LER' COVERED BY ■ • . •.

•' *• ■ .' ] FIRt OF l/PPER GUN . • ." ■•

area in pl.-.he of purs0er"5 propelter
through which upper gun cannot pirc
Without damac«nc own tail '

How the Gotha Gunners protect the rear or "blind" side from attacks.

The German Gotha battleplane, famous for its raids on British soil.

TEXTBOOK OF MILITARY AEROXAUTICS

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cations of a section for this reason : although the
greater part of the hnes are laid by the signal
companies, when once laid, the balloon section
is responsible for their upkeep, and it will be
seen, on referring to the sketch, that it is a
pretty big job for the small telephone detach-
ment allotted to a balloon section. Therefore
it is of the greatest help when batteries assist,
as much as is in their power, with the laying and
maintenance of the line from their position to
the advanced exchange ( see Fig. 1 ) .

The work chiefly allotted to the balloon con-
sists of:

1. Destruction of villages;

2. Destruction of strong points behind the
line;

3. Registering on cross roads;

4. Registering on exits from villages, woods,
and ravines;

5. Counter-batterj' work.

The method of observation employed it to
observe on the line balloon-target, and, bj' the
use of graticuled glasses, to send to the battery
such observations as

1°20' Right,
30' Left,

Line and over.

Line and short.

When the battery sends "Gun fired," the
chart room officer sets his stop-watch going and
says, "Bun fired" to the observer, then, at the
correct time: "10 seconds to burst"; "5 seconds
to burst"; "4"; "3"; "2"; "1"; "Burst."

This relieves the observer in the balloon of
watching with his glasses the whole time. He
nmst keep his eyes fixed on the target, but need
not strain them by peering through his glasses
during the whole time of flight. When he hears
"10 seconds" he gets ready, and at "5" puts
them up.

A French captive balloon of the Caqout type just behind the firing lines.

CHAPTER VII
KITE BALLOONS -THE EYES OF THE ARTILLERY

Written by a French Officer; Translated by Augustus Post
(From "Lectures Pour Tous")

Another of the marvelous developments of
the war is the captive balloon, which, in view of
the wonderful progress made with dirigibles
and aeroplanes, seemed doomed to be relegated
to the storehouse. Captive balloons, on the
contrary, have developed with the increasing
importance of artillery until we now receive
most valuable service from our "sausages,"
which are exposed to great dangers and whose
officers have had most dramatic adventiu'es.

Holding the lines of the enemy under con-
tinuous observation, transmitting to the com-
mander every operation that goes on, directing
artillery fire — this is the role that the captive
balloon plays. Before the beginning of the
war, the Germans had foreseen their value and
although we had only spherical captive balloons,
they were already using the elongated shape,
familiarly called "sausage." As is the case
with many other inventions, this model was
originally French, and was copied and adapted

by the Germans under the name of "drachen,"
or "kite" balloon. It has proven its superior-
ity since the spring of 1915, because it acts ex-
actly as a kite and is supported by the force of
the wind, when a spherical balloon woidd be
beaten down by a wind of from eight to ten
meters a second.

Manoeuvering

A balloon company consists of a crew, who
take charge of the manoeuvering of a kite bal-
loon; that is to say, filling, observation, trans-
porting, and making the ascension. In addi-
tion, there are several wagons and automo-
biles. The most important is the "voiture-
treuil," or "windlass wagon." A steel cable
about the size of a pencil, that can stand a
heavy pull, is wound up on an immense reel. In
the center of this cable is a telephone wire, con-
necting with the basket. A motor turns the reel

TEXTBOOK OF MILITARY AERONAUTICS

in one direction or the other to allow the balloon
to ascend, or to draw it down. The automobile
windlass has almost entirely superseded the old-
fashioned steam winch with six or eight horses ;
it moves three or four times as fast, needs not
more than ten meters to turn, and is less vul-
nerable. Always ready, it is easily concealed
with a cover of branches.

Camp Equipment of a Kite Balloon Unit

^^^len the balloon is in use, the "treuil" is ac-
companied by a "camion aux agres," or "rig-
ging truck" containing a store of extra ropes,
the basket, the "godets," or cup-shaped pieces
which are attached back to back and make an
immense kite-tail to head the balloon into the
wind. The equipment includes the field-
glasses, maps, and scientific instruments. Be-
sides the windlass wagon, there are two equally
important wagons that hold the encampment
paraphernalia and the telephone equipment.
The first has all the things necessary to set up
a new observation station when the old one has
to be abandoned for some cause — shell-fire, for
instance, coming too near. They carry cork-
screw stakes and pegs which hold the stays of
the balloon, sacks of ballast, a ground-cloth to
prevent the balloon touching the ground, and
all the other things that are a necessary part
of the equipment. In one day a company
changed its location four times, because the posi-
tions were shelled each time after the balloon
had been set up and inflated.

The telephone car contains all the material
necessary to establish communication, — miles of
wire, apparatus, tables, bells, spurs for climbing
high trees, insulators and brackets for laying
lines to connect the balloon with the commander
of the artillerv or batteries of anti-aircraft ffuns,
if they are a long way from the place of ascen-
sion.

An Artillery Captain's Experience

During an advance, the observer in the basket
is directly in touch with the gunners and regu-
lates their fire, a very interesting occupation for
the observer, especially when it is necessary to
pick off some convoy or troop on the march.
One day an old captain of artillery who had lit-
tle confidence in the usefulness of the captive
balloon was invited to ascend, in order to see
how easy it was to control the artillery fire.
They had not ascended one hundred meters be-
fore he marveled at the panorama, at three hun-
dred he was converted, at eight hundred he was
enthusiastic. The observer who accompanied
him kept revealing new possibilities to him all
the time. The time passed until the ofiicer com-
manding the company of the balloon corps saw
his telephone operators bursting with laughter.
He called them to order, thinking that they were
telling each other funny stories, but one of them
said to him, "Take the receiver and listen to
the observer and the captain in the balloon."
They were directing fire upon a long train on
the march, at the extreme range of a battery.

One of the monster
British guns on the West-
ern front. The efficiency
of these guns Hei>ends en-
tirely on the spotting of
tlie (lerial ohservers, there-
fore. The Kite halloons
are usually stationed in
the rear of heavy artil-
lery, held anchored by
means of cnhles. The ob-
servers in the basket of
the balloon have a clear
view of the enemy's posi-
tion and observe the re-
sults of the gun firing,
and advise the battery
commanders by telephone.

KITE BALLOONS— THE EYES OF THE ARTILLERY

Photograph taken from kite balloon showing how the earth appears to an observer.

The captain was amazed and could not restrain
himself. "Bang! in the center; one wagon de-
molished. Oh! and the horses — bang! — an-
other. Eh! — Ah! it is wonderful, wonderful.
I never believed it. Bang! At least, we do not
fire blindly."

Personnel of Kite Balloon Company

The personnel of a company of balloonists
is divided into two classes of about equal num-
bers; that is to say, the men who pull on the
ropes, and the others. In order, they are: the
captain, sometimes a lieutenant, in command of
the company. It is he who, assisted by his offi-
cers, chooses the best point for observation and
the most convenient for locating the balloon and
the camp. Under the direction of the officers,
the sergeants assign the corporals to their ropes,
and lay out and transport the balloon over ob-
stacles. Eight men handle the envelope, and
the rigging, place the basket, and adjust the
maps and instruments, four or five mechanicians
work the winch, and one cyclist and one motor-
cyclist serve as messengers. As in all other
troops, there is a doctor, a quartermaster, a fur-
rier, tailor, shoemaker, barber, orderlies, and all

the little world of specialists who go to make up
an efficient unit.

Preparations for Ascension

When a company arrives at a new position
the captain, accompanied by his observers, im-
mediately gets in touch with the commanders of
artillery, inquires the location of the enemies'
batteries, their habits and activities, and the
strength of their artillery and aeroplanes. In
another direction a mounted officer with a detail-
map searches for a good location to station the
balloon. This is a very delicate matter to de-
cide. The best place is in a forest, which pro-
tects the balloon from high winds. Trees are
cut down to make a clearing large enough for
the manoeuvers of ascending and descending
without risk of tearing the envelope on the
branches, and for leaving room to handle the
tail of parachutes. Next the work of making
camp is begun. The ground-cloth is spread, ten
stakes set, to attach the balloon, 80 ballast sacks
of ten kilos are placed with their hooks in the
network, and a bag containing the balloon is
placed in the center of the ground-cloth. The
valve is attached, the cords straightened out,

TEXTBOOK OF MILITARY AERONAUTICS

and the filling pipe securely connected. All
this takes about half an hour, and the balloon
is ready for inflation. Hydrogen is brought in
from the tube wagons, each tube containing 150
cubic meters of gas, compressed to a small vol-
ume. It takes over one hundred tubes to fill the
balloon, and from two to three hours, unless you
have enough tube wagons, when it can be done
in half an hour. When filled, the "sausage" is
ready to ascend, if the weather permits and the
wind is moderate.

In fifteen minutes the balloon is in the air, not
to come down till nightfall, and the regular rou-
tine of life begins. At daylight the company
return to the balloon. Some detach the ropes
from the fastenings and unhook the bags of bal-
last which hold it down, while others connect
the appendix, and replace the gas lost during
the preceding ascension by expansion, due to the
altitude. This takes only fifteen or twenty min-
utes at most, and soon all is ready for another
ascension. When circumstances permit, the
balloon remains in the air all the time, with one
or two observers who take their meals with them.
As night falls, or when the weather renders it
useless to remain in the air, or dangerous storms
with rain or high winds, come up, the balloon is
brought down, disconnected, and made fast for
the night under the watch of sentinels, so that
the rest of the men can return to camp. Fre-
quently, it is necessary to remain ujj all night.

to search out the batteries of the enemy by the
flashes from his guns. An observer who has
passed many days in a balloon becomes famihar
with the countrj^ and can determine in the dark
various points in the landscape and tell where
certain woods and villages lie, or he can even lo-
cate very exactly a batterj' whose position could
not be located in the daytime. This routine con-
tinues with great regularity, until the company
receives orders to take up a new position. In
three or four hours at most the convoy is on the
march, the balloon being deflated in twenty-five
minutes, and packed in its sack, and all other
materials loaded on the wagons.

What You Can See from a Kite Balloon

Here is a story of a lieutenant of artillerj^ on
his first ascension.

"The order to 'let go' has been given. ]My
basket is a charming little boudoir, hardly big
enough to take two steps in. At my hand, hter-
ally, are three binoculars, maps, and the tele-
phone which connects with the ground and puts
me in direct connection with the commander of
the artillery station. At my feet, I see my com-
panions looking up, with their heads thrown
back. The perspective rapidly extends. The
horizon, limited by the trees and surrounding
hills, slips farther and farther away; the land-
scape stretches out below in relief; the picture
changes to a geographical map, but the map is

One of the hundreds ot French motor batteries en route to its firing point, the Are of which is directed by Kite balloons and

aeroplanes.

KITE BALLOONS— THE EYES OF THE ARTILLERY

vivid and brilliant with soul-inspiring color ; ser-
pentine roads and rivers stretch away in the dis-
tance. Just below me is a farm, and those mi-
nute dots are animals. In the east, a few kilo-
meters away, are the zigzag lines of the enemy's
trenches ; they cross and re-cross. In the center
runs a slender green ribbon which seems to be
intact. This is the ground between the trenches
of our first line, and the enemy. Here and
there are some ruined villages, the houses de-
mohshed. The desolation of the scene makes
one feel sad. Scattered all about, we can see
black and white places. These are the shell-
holes, where the enemy has trained a battery
upon some spot and sprinkled it with terrific fire.
There are also our own works, and batteries
which we know well by the puffs of smoke when
the guns are fired. From the basket all this is
perfectly clear. It is the ideal observatory for
artillery. It is true that the basket is not al-
ways above the positions of the enemy, as is the
case with the aeroplane, but it is stable, and you
can use glasses without difficulty. There is also
another great advantage in that the observer is
in constant communication with his batteries,
which is more accurate and rapid work than in
the case of the aeroplane."

Aeroplane vs. Captive Balloon

The captive balloon has a dangerous enemy —
the aeroplane. When the weather is clear and

An aeroplane having approached the balloon, the observer has
jumped into space and is descending by means of the para-
chute.

the clouds high, the aeroplane is not a formid-
able enemy. The telephone signal and white
pufPs of smoke from the "75's" give warning
from afar. If the balloon is too high, it is
hauled down 300, 400, or 500 meters, but not
down to the ground, for if it is on the ground,
the enemy aviator has only to consult his map

A French Kite balloon
being inflated. The Ger-
mans were first to em-
ploy Kite balloons for
directing artillery fire.
The Allies promptly
adopted them and now
there are thousands of
Kite balloons in use on
both sides and are con-
sidered absolutely inval-
uable. The English call
it "Kite balloon," the
French "balloon captif"
or "saucisse," the Russian
"Kolbasa," the German
"drachen," the Italian
"Pallone — Cervo Vo-
lante."

TEXTBOOK OF MILITARY AERONAUTICS

and altimeter to know his exact lieight above his
target and release his bombs with some chance
of success. If the balloon is at an unknown
height, it is impossible for the aviator to calcu-
late the instant to let fall his projectile. When
he descends low enough to attack with his ma-
chine gun, he must risk being hit by the ob-
server's gun-fire and the machine-gun below the
balloon. Descending to 2000 meters is dan-
gerous for the aviator, but there are some excep-
tions of which the following incident is one :
Last jNIarch, in ideal weather, the balloon of

the Company was in a clear sky at sunset.

Suddenly the signal came that a German aero-
plane was seen on the horizon. In truth, all one
could see was the white puffs from the "75's"
shells, high in the sky. But soon the silhouette
of an aeroplane appeared, making right for the
balloon. A whistle, two or three sharp com-
mands, and the windlass commenced to haul in
while the machine-guns and muskets were
trained on the aeroplane, and the observer
warned by telephone. There was no more
doubt, for not only had the aeroplane headed for
the balloon, but again, without heeding the
bursting shells, pointed directly at the "sau-
sage." Descending with great daring to the
same height, so that it was difficult for the anti-
aircraft guns to regulate their fire, the machine-
guns only were brought into action. In the
basket Adjutant T., just promoted, prepared

to christen his chevrons; his carbine came into
play. Seeing the balloon descend, the German
aviator volplaned down, so near that we hoped
each instant he would be caught in the manoeu-
vering rope. While turning, the aviator was
furiously firing his machine gun. As luck
would have it, the carbine of the observer
jammed. He kept cool, however, which was
easily done, for it was 6° above zero, and calmly
sat down in the bottom of the basket trying to
fix his gun. Believing him wounded the
"boche," despite the bullets which whistled
around him, tried to set fire to the "sausage"
with a specially constructed cannon. He
launched an incendiary bomb, and we saw a
train of glowing sparks go toward the balloon.
But Adjutant T. had fixed his gun. He rose
in the basket and fired point blank at the enemy.
Alas ! he fired only four shells when the breech-
block broke, leaving him completely disarmed,
while the German, with a new machine-gun,
merely unrolled a new belt of 250 cartridges.
Finally a French aviator, who had seen the
struggle from afar, flew up to the rescue. The
aviatik flew away, pursued by the "75's."
Brave Adjutant T. was safe and sound, but the
basket and envelope were riddled with bullets.
This damage was repaired with a few patches.

Such a bold attack is exceptional, but some-
times the aviator uses other tactics to attack the
balloon. He chooses a day when great clouds

A Russinn observntion balloon
and its "nurse." An oljserva-
tion balloon after inflation may
stay in the air for an entire day
without receiving additional gas.
When it needs replenishing a
smaller balloon, the "nurse," is
brought up and the gns it eon-
tains is pressed info the larger
balloon, the pressing being done
by the men, who squeeze the
"nurse."

KITE BALLOONS— THE EYES OF THE ARTILLERY

form in a layer above the balloon, two or three
thousand meters high. Flying above the
clouds, the aviator, seeing his prey through a
rift, or judging he is near enough, darts down,
releasing his incendiary bombs covered with fish-
hooks, which catch in the envelope and are sure
to set it afire. Another of these tactics is to
take advantage of the clouds that pass between
the balloon and the ground, hiding the aeroplane
from the eyes of the balloon company, who are
unable to train their machine guns upon the
enemy.

A Leap Into Space from a Kite Balloon

Experience has taught that the counter -move
for this manoeuver is not to allow the balloon to
rise out of sight above the clouds and, when
necessary, to haul it down by the winch every lit-
tle while. The observer is also provided with
a parachute, which he attaches to his back by
stout suspenders which pass under his arms and
around his waist. If he finds his balloon on fire,
or if warned by the telephone from the ground,
he jumps out. The parachute, folded in a spe-
cial sack, opens in less than sixty meters, land-
ing him gently on the ground. This is of quite
frequent occurrence. Within three days the
life of an observer was saved on two occasions
by this means. On the 19th of March, during a
violent wind-storm, the rigging broke, and two

The observer descending with the parachute to escape an aero-
plane attack.

seconds later the basket started to fall. In-
stinctively the observer saw his danger, gathered
up his papers, jumped into space and descended
with his parachute. When his feet touched the

Turning on the gas
from gas cylinders to in-
flate a Kite balloon.
M'herever a Kite balloon
is established there are
brought the gas cylinders
on specially constructed
trucks. They are then
unloaded and placed on a
.special stand, as shown in
the photo, and pipes are
connected to each cylin-
der and to the main pipe
which is connected to the
rubber tube which leads
to the ai)pendix of the
Kite balloon.

TEXTBOOK OF MILITARY AERONAUTICS

Members of the Canadian Kite Balloon Section patcliing up a
kite balloon on the Somme front.

ground, the eighty square meters of cloth made
a sail in the strong wind and he was dragged
1200 meters over the fields, finally bringing up
with only a few scratches.

A Curious Manoeuver

"When the wind rages and the rain falls, the
windlass is used to bring the balloon down, but
if it breaks, they use a "tiraudes," or snatch
block with eight large ropes attached to it.
!Men pull on this rope, marching straight away,
bringing the balloon down to the ground one
half as fast as the winch. A serious situation
may arise if the windlass is destroyed by shell-
fire and the balloon cut away when the wind is
blowing toward the enemy's lines. When this
happens, they move the automobile winch away,
dragging the balloon like a kite. Of course the
observer can always descend by opening the
valve and allowing the gas to escape.

A Drama at the End of a Cable

Accidents will happen despite all precautions.
Last spring there was a tragic day for our bal-

loons when several were torn away by the wind
and driven over the enemy's lines. The weather
kept the balloons down all day until about 5 :30
P. M., when it cleared and the wind fell to a flat
calm, the kite tails hanging vertically along the
cable. Two officers went up in one of the bal-
loons. They wished to go high enough to ob-
serve a battery that had had the cover which con-
cealed it blown away. To lighten the balloon,
they left the only parachute in the equipment
on the ground. Suddenly the telephone op-
erator called the observer and said, "Heavy
clouds are forming in the southwest." Rapidly
the sky became overcast and in an instant the
balloon, which had been hanging directly over-
head, started northeast. The wind rose, and
the Captain ordered the windlass to haul down
as quickly as possible. Two hundred meters
were wound on the drum, and a thousand still
remained. The winch puffed and labored, and
finally stopped altogether. "Raise the pres-
sure," ordered the Captain. "I have eight kil-
ograms," answered the engineer. The pressure
cannot be raised in a moment, and time was fly-
ing. The windlass turned slowly, and again it
stopped. "Ever}" one on the hauling ropes,"
came the order, as a last resort. Two hundred
meters were hauled in this way, when the men
walking away with the rope were blocked by a
large farm building and had to halt.

At this moment the engineer signaled that the
pressure was at ten, the extreme limit of the
gage, and again the winch began to turn.
Hopes arose, but the wind arose, too. The rope
jumped the groove of the pulley, became
jammed, and the winch stopped. "To the haul-
ing ropes again," the Captain cried. INIean-
while there was another drama at the other end
of the cable on which hung the life of two men.
The "sausage" tugged at its mooring line, like
a horse champing his bit. The basket swayed,
capsized and swung like a .stone in a sling. The
telephone was not yet broken. From the bot-
tom of the basket one of the unfortunates
shouted, "One more jerk will be our la.st." The
other cried, "It is all over with us." Alas, his
presentiment was only too true. The basket
tossed in the air. The .stabilizing wings of the
balloon were torn off. The balloonet ripi)ed

KITE BALLOONS— THE EYES OF THE ARTILLERY

into shreds, diabolically whipping the air. One
after another the strands of the cable broke.
The balloon, freed from its leash, leaped into the
air, the light car swaying below. It was a tragic
moment ; there was a lull in the midst of the con-
fusion, but the poor men in the basket were per-
fectly calm. No more jerks terrified them, but
what was worse, they were borne in the direction
of the enemy's line. We saw objects fall from

the car. They were, as we found out later, the
maps and secret papers which the brave men had
had the presence of mind to think of and throw
down before passing over the lines. This
drama had taken only thirty-five minutes. The
"sausage," which the Germans fired at as
it came down low over the trenches, landed,
and the French officers were made prison-
ei's.

Memoranda:

TEXTBOOK OF MILITARY AERONAUTICS

The trenches and shell lioles and advancing; allied troops photographed by an allied aviator.

How aero photofiiaphs ai<- put tci;;. Iher to make a continuous photographic map. These photographs were taken by Allied
aviators at the Dardenelles the early part of the war. The city of Tchanak and the estuary of the Kodja Chai; on the right shore
is fort Tchimalik and on tlie left fort Hamidie.

CHAPTER VIII
AERO PHOTOGRAPHY

In the official reports of military and naval
operations in the present war daily items can be
found reading more or less as follows :

On May 20th the French prepared to rush the im-
pregnable positions on Mount Cornillet and Mount
Teton. Photographs taken by their aviators showed
an immense system of tunnels which apparently con-
cealed German reserves. A single entrance was lo-
cated and the operator of a French 15-inch gun ten
miles away was told to put a shell in the entrance.

The gun started firing thousand-pound shells, and
the infantry was ordered to advance at a certain
minute. Two hours before the time set for the ad-
vance a half-ton shell planted itself squarely in the
mouth of the tunnel, killing half of the men inside,
blockading the exit, and wrecking the transverse cor-
ridors. The French advanced and took several hun-
dreds of prisoners without suffering any loss.

Thousands of Miles of Photographic Maps

The mihtary and naval authorities of the
warring countries have thousands of miles of
photographic maps. These are kept up to the
minute by the constant stream of aerophoto-
graphs brought to headquarters by aviators,

where they are developed, studied, and the mi-
nutest changes noted on the map.

The following report gives an idea of how
exact a science aerophotography has become,
and what its value is in connection with military
and naval operations :

Several series of photographic plates, taken by
British naval observers after the bombardment of
Ostend by the British forces on June 5th, have
arrived at the Admiralty in London and afford a
remarkable example of the development of photo-
graphic observations and record by aeroplane. They
show in undeniable fashion that the British bombard-
ment of Ostend on that date was the most successful
thing of its kind yet accomplished, insuring that
Ostend will be crippled as a useful German base for
weeks, if not permanently.

The first series shows the German base before the
attack, while a second group shows the effects of the
bombardment. In the pictures of the harbor one is
immediately struck by a slight change in the appear-
ance of the great lock-gates on which all the activity
of the harbor depends. These gates are 100 feet
long and 25 feet high, and they seem somehow to
have lost a little of their rectilinear character over-
night. The magnifying glass reveals some of the
reasons for this change. The breaking down of the

TEXTBOOK OF MILITARY AERONAUTICS

One of the large French apparatus for taking photographs from
aeroplanes.

locks prevents the retention of water in the basin and
the canals which feed it, incapacitating the entire port
machinery. Equally effective in crippling the harbor
is a hit on the operating machinery, jamming the
locks so that ingress and egress is impossible until
elaborate repairs are made.

The pictures confirm tiie statement in the official
communique that more than half the buildings in the
factory section of the town have been either destroyed
or badly damaged. It is easy to see that there may
have been a heavy loss of life, although the residential
section apparently was untouched. Some of the
ruined factories necessarily operate night and day
and many men are employed at night on the shipping
and docks. British shells, dropped from a height of

miles by the high-angle fire of the British monitors,
located at a point far below the horizon, frequently
fell straight through the roof of a shed or factory,
blowing out great sections of the sides and roofs and
hurling a shrapnel-like shower of splintered wood,
steel and rock into the adjacent buildings.

Twenty Per Cent, of Aeroplanes at the Front
Used for Aerial Photography

Every military operation is preceded by an
extensive photographic survey of the enemy's
position and hundreds of photographs are taken
by the aero photographers, until headquarters
has obtained all the information necessary to
complete the photographic map upon which the
operation is to be based. , Fully twenty per
cent, of the aeroplanes used at the different
fronts are employed in taking photographs of
the enemy's positions.

For this purpose are usually employed ma-
chines having a speed of about eighty miles an
hour, and the aerophotographer must go down
as low as jjossible over the enemy's lines, with-
out actually going below the "safety" point,
which varies under different circumstances.

When one side has command of the air, and
there are plenty of fighting machines about to
keep the sky clear of enemy aeroplanes, the task
of the aerophotographer is comparatively easy,
because he only has to contend with the enemy's
anti-aircraft guns. Firing these is not always
thought advisable by the enemy, as it gives the
location and range of the batteries to the kite
balloons and artillery aeroplanes of the other
side. Till recently the aerophotographer was
sent out in a fairly slow aeroplane, with a num-
ber of fighting-machines to protect him. The
fighting-machines, flying at a speed of about

1
i

■■'^^^ ! ^^''^iSHPiHB? ^

■ ft ... - ,-' . Ill m M\ ''iMSBtBf^^

A French machine used for pho-
tography in 1917.

AERO PHOTOGRAPHY

Side view of one of the Farman aeroplanes used for aerial photography.

120 miles an hour, would fly around in circles
looking for enemy machines, while the photo-
graphing-machine went about its business of
taking photographs. But oftentimes a lonely
German aviator, who had taken his position high
up in the sky while waiting to dive on Allied
aeroplanes, in accordance with the tactics estab-
lished by Immelmann and Captain Boelke,
would spy the slow photographing-machine and
dive for it, shooting as it drew near and landing
immediately, whether it brought down the pho-
tographing-machine or not.

In this case the fighting-machines which es-
corted the photographing-aeroplane were un-
able to defend it, because the battle was all over
before they could manceuver to a position which
would permit them to intercept or fight the at-
tacking German aeroplane. As they were fly-
ing over German territory, they could not fol-
low the German machine in its flight downward
over the German lines, because of the German
anti-aircraft batteries.

This method involved sending out from four
to six machines to convoy a single photograph-
ing-machine, but did not permit as good protec-
tion as is afforded by sending a larger photo-
graphing-machine equipped with several ma-
chine-guns mounted forward and rear. These

permit the gunners of the photographing-ma-
chine to defend themselves against attacks from
even two or three enemy aeroplanes. With this
larger type of machine the effect of an attack
does not involve the loss of the aeroplane, the
aviator, and the photographer, as in the case of
the smaller machine which is unable to defend
itself. In the former, if the photographer or
one of the gunners is hit, the other two members
of the crew can keep up the fight while flying
back to their own lines, or until reinforcements
arrive. Therefore the tendency is toward the
employment of larger and well-armed aero-
planes for aerophotography.

The Aerophotographic Organization of an
Army

Since the value of aerophotography became
recognized, the armies in the field have had spe-
cial aerophotographic corps. The size of these
corps has been increasing steadily.

As many of the American aviators now being
trained, or to be trained, will undoubtedly be
employed in photographic work, the following
detailed description of the British aerophoto-
graphic organization will be of great assistance
in giving the student a comprehensive pen-pic-
ture of this work.

TEXTBOOK OF MILITARY AERONAUTICS

Seven Aeroplane Bombs Photographed Soon After Release by the French Aviator

That Released Them on a German Plant

The above is one of the most remarkable snapshots of an aerial bombardment. It Is an enlargement of a photoirraph taken
by a French aviator at a heipht of over 13,000 feet during a raid on a German nmnitions jilant between Metz and Briey, in the
occui)ied part of Ixirraine. The bombs are shown the moment after they were released from the aeroplane, and by reason of the
persiK-ctive ajipear as if they would fall in different directions far from the object aimed at. But the aviator has to throw the bombs
in such a way as to allow for the fact that he is traveling at a great speed and for what corresponds to the trajectory of a projtx--
tile from a cannon. The bombs used for aerial attacks are known as "M" (Michelin) bombs, and are of two kinds, weighing from
20 to 100 ]K>unds. In this case all the bombs were thrown together and succeeded in hitting their object, the German munitions
factory 1h-1ow. The district chosen for attack is a great manufacturing region the Germans liave turned into a huge war factory.
The British and French armies arc confining their air raids exclusively to military ol)jects, such as the bombing of the sulnnarinc
establishments l>ehind the German lines. Although we receive reports of only the more important aerial attacks, these attacks are
of daily occurrence, and have caused far more tlamage than the Germans care to admit. (French Official Photo.)

AERO PHOTOGRAPHY

Aeroplane Photography That Shows Minutest Details of a
Factory Chimney Being Repaired !

M^*

This remarkable photograph taken from a French aeroplane shows how the Allied aviators can fly low and choose their
target in bombing German munition plants, provided there are sufficeint aeroplanes to fire on and silence anti-aircraft batteries.
Also the clearness of the target on an aerial photograph for use by the artillery.

TEXTBOOK OF MILITARY AERONAUTICS

Film-picture taking in mid-air: a piiotographer and liis cameri
in a icite-balloon.

The prints are kept in wallets in series b\
squadrons, e.g., all Xo. 25 squadron prints from
2.5 w 1 to 25 w 1000 would be kept in this serial
order in probate wallets.

Thus it is possible to refer to photographs in
every way by date, squadrons, area, and so on.

Cioiiifi uj) ill a Ciuqiiul halliim. l.» ..Imcrvc artillery firing in
France, and taking photos at close range.

* ni. . L- nttc OL ij L c- -1. How scale varies with height, and focal

A Photographic Urricer Should be ramihar i +1 f i
u/:iL ..u- c-ii :__ T I • _i o__L- -1- lengtn or lens.

With the Following Technical Subjects

Detection from prints of bad work; differ-

The necessarj' accommodation for the work at ^"^^ ^'^^^^^^ S^od prints from poor negatives,
present demanded from a section.

Apparatus used — function of each item — ■
which essential and which non-essential. Rough
and ready substitutes.

Construction and care of cameras. Details
of mechanism and weaknesses. Properties of
focal plane shutter, and of Anastigmatic lens.
Function of color filters, and Panchromatic
plates, advantages, and disadvantages. Causes
of failure.

Attachment of cameras to machines; advan-
tages of the various systems and the reasons.
Vibration; results of investigations in the field.

The Canadian official kineniatogniiihrr gmng iilmi in nn ob-
servation balloon.

AERO PHOTOGRAPHY

A German Scout photographed by a French Scout early in 1915 when aerial fighting was not in practice.

and poor prints from good negatives. Stains,
and their cause and cui-e.

Identification with map — this of the first
importance — recognition of roads, trenches,
tracks, wire, batteries, etc. JNIap square system
co-ordinates.

System of central registry and fihng of pho-
tographs.

Possible output of prints in a given time.
Any section should, in times of stress, be able
to send out for a week without breakdown.

Time necessarily taken by the various
processes.

Simple intelligence reading of photographs.

Cameras and Fittings

It is the duty of the non-commissioned officer
in charge of the photographic section to see
that the camera fitting is jiroperh" fixed to the
machine and to place the camera in it, adjust
slit, clear lens from dust and wind the tension.
On no account should cameras be kept in the
hangars.

Cameras can be taken from hot to cold, but
the reverse causes condensation to form on lens.
Care should be taken to avoid this, or the recon-
naissance will be a failure.

Loading of Plates

All plates should be loaded in absolute
darkness, and the metal sheaths should al-

ways be cleaned from dust and rust before
loading.

It is advisable to load magazines as required,
and not keep them loaded, as metal dust ac-
cumulates and particles of such dust set up
chemical action. Cameras should be kept scru-
pulously free from dust, which is one of the
worst enemies. Nothing spoils the appearance
of a print so much as innumerable pin holes.

Negative Developing

Discrimination must be shown not to treat
the development of all subjects alike. A town
requires less exposure than green fields, and
must be treated accordingly.

Over-development is the usual fault. In
some countries with chalky soils, much detail is
lost unless great care be shown in timing the
rate of development. A thin negative with
plenty of detail printing through the lantern
in about six seconds is about the ideal.

Finish of Work

Work is not allowed to stop on any account
until all orders are finished.

All dishes, measures, etc., must be thoroughly
cleansed before the men are allowed to leave.

Cleanliness in the dark room is essential to
efficiency.

TEXTBOOK OF MILITARY AERONAUTICS

A French photography twin motored biplane.

I.lnot of trenches on the Western front photogruj)hcd from an aeroplane. Soldiers arc shown walking along the trenches.

AERO PHOTOGRAPHY

The war-kite in mid-air.

A Squadron Photographic Non-Commissioned

Officer With His Three Men Should

be Familiar With the Following:

Details of mechanism of camera.

Properties of focal plane shutter, and An-
astigmatic lenses.

Color filters. Panchromatic plates.

Attachment of cameras to machines. Perfect
fitting is essential.

Care of cameras and lenses generally.

How to put in a filter and re-lock the lens.

Simple repairs to cameras.

Jams. How they occiu", and how they can
be avoided.

Loading of magazines in complete darkness.

Use of special size plate and sheath gage
for loaded sheaths to prevent jams.

Formulae at present in use.

Development of

How to obtain thin, quick-printing negatives
full of detail.

Value of "color." Big dishes are preferable
to tanks.

Cleanliness.

Washing and drying of negatives; use of
spirit; avoidance of spirit-fog due to sunshine
and change of temperatiu-e.

The observer and photograplier in mid-air supported by kites.

Use of hydrochloric acid to take out occa-
sional excess of color.

Printing; speed is essential. Hand-shading.
Every man should be able to make at least
good prints per hour.

Substitutes for apparatus. Gasoline tanks
as fixing tanks, etc. The excellence of old
doped fabric with which to make big dishes.

Development of prints. One man should be
able to develop at least 12 prints at once, in
one dish with one hand, and to fix them in an-
other dish with the other hand.

Washing: thoroughness.

Drying; spirit and burning-off processes.

Identification of photographs with maps.

Characteristic natural and artificial features.

Reversed writing for marking negatives.

A sound idea of the shutter slits and expo-
sures to be used. System of catalogue, and
filing.

Lantern-plate and positive making both on
sy^ by 31/4 and by contact,

Science of Aerophotography Still Young

The science of aerophotography is still in its
infancy. Up to the present time it may be said
that only existing forms of cameras, or modi-

100

TEXTBOOK OF MILITARY AERONAUTICS

The Herbert & Husgen multiple aeroplane camera.

fied cameras, have been used to take aeropho-
tographs. Little has been done to develop spe-
cial photographic apparatus to take better pho-
tographs from the air at different altitudes in
order to show in sharper detail the topography
of the country, either straight below or in per-
spective.

Essentials in Aerophotographs

The essential thing in taking aerophotographs
is to bring back a perfect record or map of the

Four type* of nrroplnne rnniprns used by tlic Frencli Air Serv-
ice. (Official Phiito, from the Illustratwl Liindoii News.)

surface below, with the component objects in
their true proportions.

The military commander mainly wants to
know:

(1) The distance between points.

(2) The location of objects, such as enemy
batteries, structures, trenches, camps, roads,
ridges, bodies of water, etc.

(3) The disposition, or traces of movements,
or actions of the enemy. If a battery is shown,
it is essential to know that it is not a dummy
battery.

(4) The elevation of ridges or depth of de-
pressions where his own forces may hide in
advances.

(5) The nature of the country, whether it is
solid ground, marshes, forests, cultivated land,
brush, etc.

To take an accurate map of the surface be-
low and eliminate distortions, the axis of the
camera must be kejjt vertical to the gx'ound.

Relative Elevations Hard to Show

Relative elevations cannot be shown in an
aerophotograph, except l)y contrast, when the
elevation occurs near bodies of water, or tlic
photograph is taken close to the ground or in
perspective.

AERO PHOTOGRAPHY

101

Whenever airmen bomb
places they must bring
back photos showing
the damage done. As
the anti-aircraft guns
begin to fire as soon as
the bombing plane is
detected, the aviator
takes the photos of the
damage as he climbs to
safe altitudes. This
photo shows buildings
on fire after bombs
were dropped.

In the last case the image is distorted, al-
though, of course, the information that it con-
veys regarding elevations is invaluable. But a
trained reader of aerophotographs can detect
elevations in the prints, as well as the nature
of the surface.

The nature of the surface is harder to detect
■even in ballooning. Messrs. Alan R. Hawley
and Augustus Post, during their forty-six-hour
balloon trip, which started at St. Louis and ter-
minated in the wilds of Canada, were deceived
by the look of the country from a height of
15,000 feet, at which elevation they were trav-
eling. It was in October and the leaves were
turning yellow. The contrast of spots where

the leaves were green, extending over miles of
country comprised in their perspective, led them
to believe they were traveling over cultivated
country, when they were, in fact, traveling over
unexplored country.

Interpreting Photographs Requires Skill

Interpreting or reading photographs requires
skill gained by long experience.

The expert "interpreter" of photographs
must be able to gage distances and elevations
at a glance, and also tell the nature of the
surface.

The camera always flattens the field and de-
stroys perspective, but the trained "interpreter"

The pistol-camera for German airmen — the right side.

The pistol-camera for German airmen — the left side.

102 4 •//;;:: -TEXTBOOK OF MILITARY AERONAUTICS

Camera mounted on a British R, E. liiplane, Major Campbell in the pilot seat, demonstrating it.

(Photo Bureau of Public Information.)

reaches a point where he is able to tell at a
glance the nature of the surface from a photo-
graph.

Problems of Aerophotography

The problems of aerophotography resolve
themselves into the one big problem of showing
the nature of the things photographed.

Thr Ragtman aeroplane cnmera.

The important factors in aerophotography
are:

( 1 ) Tiie plate. Experiments should be con-
ducted to develop special plates, so that lumi-
nosity, water-vapor, haze, and smoke can be
filtered, and good photographs taken under any
condition.

(2) The method of development.

(3) The lens.

(4) The mechanical constniction of the cam-
era and the facilities which it may afford for
taking photographs in number, with the records
of compass direction and altitude as far as pos-
sible.

(5) Skill in taking the photographs. This
has been elinu'natcd to some extent, and it
should be fiirtlicr cliininated by evolving rules
which anybody can follow in taking acroplioto-
graphs. Skill in developing the photographs
and printing them is another matter entirely,

AERO PHOTOGRAPHY

103

■n<f^

The Fabbri apparatus fitted to a fast scout.

and rules can never be the equivalent of ex- tograph, which may show up with a fair de-

perience.

(6) Edmination of vibration. Vibration is
one of the worst enemies of aerophotography.
It is hard to eliminate it entireh^ and it causes
blurs. These decrease the clearness of the pho-
tograph from ten to fifty per cent, although the
blurs are not visible to the untrained eye. Vi-
bration is eliminated by mounting the camera
on special springs, or by employing a gyro-
scopic device. Blurs, due to vibration, destroy
the photograph so far as getting minute de-
tails from it are concerned, although when
looking at the photograph one can recognize
the larger features of the landscape without
difficulty. A good photograph is like a master-
piece by Detaille, so finely and exquisitely
worked out that it requires a microscope to ap-
preciate the great wealth of detail the artist has
put into his work. On the other hand, a blurred
photograph may be compared to a picture by
Claude ]Monet, the great leader of the impres-
sionistic school, in which the salient objects
stand out clearh' when viewed at a little dis-
tance, but become onlv splashes and daubs of
color when closely scrutinized. A blurred pho-

gree of clearness to the naked eye, gives a con-
fused image when placed under a magnifying
glass.

Two aeroplane British Royal Flying Corps cameras

being returned to headquarters after a flight.

(Official Photo.)

104

TEXTBOOK OF MILITARY AERONAUTICS

An aeropiiotographer taking pictures in mid-air.

Efforts should be concentrated on developing
special plates which will permit the screening
of luminosity — caused by violet rays and pre-
venting details from showing in the photo-
graph— and fogs. There are, of course, differ-
ent types of fogs, — about half a dozen kinds, —
and some are more difficult than others to pene-
trate. On the other hand, certain tj^pes of
smoke can easily be penetrated.

As a general rule, an aerophotograph is much
clearer than a photograph taken on the ground.
This is because in photographing from the sky
there is only a thin layer of dust to penetrate,
whereas in a photograph taken from the ground
the distance between the camera and the objec-
tive is one continuous layer of dust. Different
types of cameras are used to take aerial pho-
tographs, some intended to take wide angles
and some to get the details in small areas.

The necessit}' of photographing positions
which are well protected by anti-aircraft guns
has necessitated the employment of cameras.

DritUh Naval Flvlnjf Corps stuwinti* \te\na Instnu-twl in tlu- handling of an ucropliux- iim.ra
• "^ ' "^ (Official IMu)to.l

AERO PHOTOGRAPHY

105

Different Types of Cameras

Different types of cameras are used, includ-
ing automatic cameras, which can take photo-
graphs every ten or twenty seconds.

As the United States is to supply many of
the cameras to be used in this war, it is of in-
terest to note that several remarkable cameras
are being made in this country. The newest
of these, a very efficient apparatus, has been de-
veloped by the pioneer aerophotographer, Mr.
J. F. Haworth, M.E., of Pittsburgh. Al-
though very simple in construction, the camera
takes a surprising number of photographs per

minute, and also records the speed of the aero-
plane, as far as it can be estimated, compass
directions and a record of the altitude at the
time the photograph was taken. Mr. Haworth
carried out the photo-cartographic work for Mr.
Cui'tis, the artist, who made the remarkable
geological reproduction of the Kilauea Vol-
cano, Hawaii, which is now in the Aggassiz
Geological Museum of Harvard University.
It was found necessary in this work to produce
aerophotographs with rapidity, fidelity, and
correct orientation. A special camera had to be
devised for the work. First of all, the camera-

Reniarkable photograph of the Chatnpajrne trenches taken by a French military observer during a terrific battle. It sliows
how the trenches are scientifically constructed in zigzag formation, so that if an enemy should capture them, it would be impossible
to shoot any distance down them. The earth in the Champagne district is of chalk formation, which outlines the trenches in white.
The pockmarks in the picture are where the shells have exploded.

'^— ^^'I'app with unroofed houses in the path of the war. B— Road worn by artillery and supply trains. C— The zigzag con-
struction of the trenches. D— Pockmarks where shells have exploded. E — Connecting trenches between first, second and third lines.
F — Ground between the enemy trenches.

106

TEXTBOOK OF MILITARY AEROXAUTICS

maker had to calculate the distance of the geo-
logical formations from a known basis. The
lava flow of this volcano has an area of six
square miles, and it is rich in important geolog-
ical formations. The work of the camera-
maker is more exacting, perhaps, than that of
the military map-maker. A camera was de-
vised which works automatically with its axis
vertical to the surface of the earth, and has a
wide field on either side. It is necessary to take
successive pictures and correlate them by suc-
cessive overlapping. It was found that the
magnetic north and south of each picture and
the altitude facilitated proper placing at the
scale of the formation.

The camera now available for aerophotog-
raphy remains unchanged, except that the time
of day is now reported on the photograph.
This is done automatically and the mechanism
of the camera can be set to take several pictures
a minute. A complete record of the surface
of the earth beneath the aeroplane may be pro-
cured by merely touching a lever. The camera
records the time the aeroplane goes over a given
point in the enemy's country, the compass direc-
tions, and the speed of the aeroplane as far as
it can be estimated.

Two other remarkable cameras suitable for
aero-work have been constructed by the Herbert
& Huesgen Co. of New York and the Eastman

Aero photo of n liiilitnrv nrrmlnmic, "somrwiicre in I'rniicr." sliowiii(j 17 Ihiii niuliHnl t aiiilron lH|ila]u-. iiiiil ;ilioiit JO iiiolcn- trnns-
|K>rts Itelonging to the nero Kqundriin. The seven huge hungars ciin house about (iO aeroplanes.

AERO PHOTOGRAPHY

107

« '"^^^N^.

■^ '^—"^^ ^s^ffiaEsss^"'

The Allies' command of the air on the western front, which permits Allies' airmen to map the enemy's trenches.
A French airman flew over the enemy's lines and brought back to headquarters in a few minutes this perfect map of the enemy's

trenches, with French shells bursting over the trenches.

Kodak Co. The first makes it possible to take
750 pictures with one loading. As a standard
size film is used, it may easily be projected on a
screen for military purposes.

The action of the camera is automatic.
One pull of a flexible cable sets the shut-
ter, makes the exposure, winds up the pre-
vious exposiu'e and registers the number of pho-
tographs. It is universal in focus. The lens
is exactlj' the same as that used by professional
operators of motion picture cameras, being the
highest grade astigmat, with a speed of f.4.8.
It is easy to operate, and the military aeropho-
tographer can take hundreds of photographs of
important positions in quick succession and yet
operate a gun to defend himself. This camera

weighs only 6 pounds and is constructed entirely
of metal and, therefore, is not easily broken.
Altitude photographs may be taken with this
camera from a height of 10,000 feet with a lens
of special focal length, supplied with the cam-
era. jVIotion-pictiu'e films of standard make are
used, which give minute definitions and great
capacity in a small space.

Film vs. Plate

On accoimt of its lightness, unbreakability,
and simplicity, the film is preferred for aerial
work, especially since there are cameras which
permit loading for hundreds of exposures. The
possibility of turning out films which give as
good results as plates is excellent. A great ad-

108

TEXTBOOK OF MILITARY AERONAUTICS

Possible Troubles in

Taking Aero

Photographs and Their Remedy

FaulU.

Probable Cause.

Remedies.

Plates fogged.

leakage.

Examine all screws on cone,
changer and lens plate.

Open silt In blind and place
an electric lamp Inside
the cone and examine for
light In the dark room.

Take off changer, and fit
the magazines with lids
open, place a lamp In-
side the magazines and
examine for leakage be-
tween magazine and
changer.

Examine also the magazine
lld.s.

Movement on

Slit too wide.

Examine cord, pulley plate,

plates.

Shutter sticking.

teeth on "set" wheel and

Bad fitting on machine.

pinion.
Examine blind and notice If
the slit Is true.

Negatives out ol

Lens working out of

Tighten up, re-focus, and fit

tociu.

flange.

grub screw.
Test with gage.

Sheaths not dropping

true on changer

Test with sheath In gage.

slide.

Changer Jam-

Changer handle not be-

ming.

ing pushed forward
to end of movement,
and not allowing the
plate to drop clear
of the aperture In
changer slide Into

receiving magazine

Take camera oft machine.

Sheaths being Inserted

In the wrong side of

and turn upside down, al-

the magazine, thus

lowing sheaths to drop

allowing the open

back In the magazine.

edge to jam In the

Close lid In this position.

forward movement.

and re-fit the sheaths In
their proper position In
the magazine.

Changer working

Small chips of glass

Take off top half of changer

sttn.

worked Into changer.

and clean out ; oil run-
ners.

Take oft top half of changer,

Changer handle bush

working loose.

remove changer slide
plate, and tighten screws
holding bush on to plate,
file off any protruding
screw ends on reverse
side.

Pulley bracket slide

Take off inspection cover

not working freely.

and examine.

Changer handle

Shutter setting cord

Release retainer screws and

not able to fin-

too tight.

allow handle to finish the

ish vbole ol

forward movement, then

forward move-

pull In cord enough to

ment.

give a V4. turn on pinion.

Changer working

Cord retainer screws

easily but not

loose.

setting ihutter.

Broken cord.

1. Remove the changer

2. Take off "set" Indicator

comer plate ; the pulley

on shutter pinion will

now be exposed.

3. Thread the cord from

the Inside of the pulley

through the hole on the

Probable Cause.

Changer working
easily but not
setting shutter.
Continued.

Releasing lever
not working
freely.

Sheath not pass-
ing through
changer.

Changer Jam
mlng at end of
forward stroke
of handle.

Changer handle
Jammed at re-
leasing posi-
tion.

Broken cord.

Camera being fitted on
outside of m/c and
having a cord on re-
lease lever which Is
exposed to the wind.
Induces a resistance
which the lever can-
not overcome.

Setting pin In pulley
bracket slide broken.

Changer Inlet and out-
let being of wood
are liable owing to
damp to swell.

Changer slide plate
jamming between
top half of changer
and the small stop-
lips on the end of
runners.

Sheaths fitted In mag
azlne wrong way.

Remedies.

roller side thereof, and
secure by means of a
knot. Wrap the cord
around the pulley five
times, first passing it un-
der and then over the
groove.

4. Thread end of cord
through eyeletted hole In
the corner plate.

5. Replace corner plate and
changer.

G. Pull cord, so as to set
the shutter.

7. Pass cord around sliding
pulley on changer and
push up changer slide as
far as it will go. and ad-
just the cord to the cord
grip which is attached to
the corner plate.

S. To Test. — Release shut-
ter and re-set by means
of the changer slide han-
dle. If the shutter does
not set, the cord is not
tight enough, and must be
adjusted by pulling a lit-
tle further through the
grip.

N.B. — It is very important
to notice that while it Is
necessary to have a cer-
tain amount of tightness
on the cord In order that
this shutter may set, it is
equally Important that
this tightness should be
only just sufficient to set
the shutter, as other-
wise, when working the
changer, the cord lt.self
acts as a stop for the
travel of the changer-
handle. Instead of the
handle slotted plates.
The result Is that the
cord will snap with the
greatest of ease. If the
cord Is properly adjusted
so that It does not act
as a stop to the travel of
the changer, the cord will
last a long time.

Fit additional spring from
lever to cone.

Release cord from retainer
and take off pulley
bracket slide and re-fit
pin.

Test with changer gage and
ease woodwork.

Bend the stop-lips, UkInK
care the changer plate
has the full movement
forward when refitted.

AERO PHOTOGRAPHY 109

vantage will be gained by developing an effi- exacting. Instructions for operating a camera
cient film to replate plates. The demands made under these extraordinary conditions are as
upon a mihtary aviator at the front are very follows:

Memoranda:

110

TEXTBOOK OF MILITARY AERONAUTICS

;ular (hiily rcionnaissancc was ciinductccl between Columbus, X. ,M., and Colonia Dublan, Mcxicd, tlu- headquarters of General
Pershing's punitive expedition and other points by the first aero squadron during the Mexican trouble.

CHAPTER IX
RECONNAISSANCE AND CONTACT PATROL WORK BY AEROPLANE

Wellington said: "Victory belongs to the
commander who makes the best guess as to what
is happening on the other side of the hill," and
winning battles has always depended mainly on
quickly obtaining accurate information concern-
ing the enemy.

Until the advent of aircraft, military opera-
tions depended largely on skilful guessing.
This guessing was made necessary by the fact
that scouts, whether mounted or on foot, could
only observe the movements of a fraction of the
enemy's forces, and the length of time required
for scouts to report their observation was suf-
ficient to permit the movement of army corps in
an entirely different direction than that re-
ported.

Aircraft, by permitting a scout to observe the
enemy from a height where the composition and
disposition of military forces can easily and
quickly be estimated, have removed the neces-
sity of guessing; and by making it possible for
air scouts to ti'ansmit with a sixty to one hun-
dred miles per hour speed the movements of an
army which can travel at a rate of only fifteen
to twenty miles per day, they have removed the
elements of surprise.

Balloons were used for observation as early as
1794. At the battle of Fleurus, June 26, 1794,
the French employed captive balloons, and
thereby gained a decided advantage over the
Austrians. Balloons were used in practically
every war thereafter. During the Franco-Ger-
man War of 1870-71, sixty-six balloons were
sent up by the French from besieged Paris be-
tween September 23, 1870, and January 28,
1871.

Five Types of Reconnaissance

Reconnaissance consists in gathering infor-
mation from actual observation. The air scout
must report facts and may draw conclusions, but
must not report conclusions instead of facts.

There are five types of reconnaissance, as fol-
lows:

(1) Distant reconnaissance, which is essen-
tially an examination of the enemy's country for
about 100 miles, made for the general staff for
strategical purposes. This is Line Reconnais-
sance and deals more with the enemy's general
location and apparent purpose.

(2) Close Reconnaissance, which is more

111

112

TEXTBOOK OF MILITARY AERONAUTICS

minute in detail and extends about 30 miles into
the enemy's territoiy. It is more tactical and is
intended for the use of the local staff. This is
area reconnaissance and deals with the details of
the enemy's position and defenses.

(3) Local or artillery reconnaissance, which
is a minute examination of the trenches and de-
fenses. It is seldom more than 8 or 10 miles in
extent.

(4) Special reconnaissance, which includes
obsen-ations for artillery spotting, locating new
targets, and other special purposes.

(5) Contact patrol reconnaissance, which
aims:

(a) To keep headquarters of formations in-
formed as to the progress of their troops during
an attack.

(b) To report on the positions of the enemy
opposing the advance, the movements of his im-
mediate reser\'es, and the state of his defenses.

( c ) To transmit messages from the troops en-
gaged to the headquarters of their formation.

Procedure in Issuing Orders for
Reconnaissance

The following is the normal procedure in issu-
ing orders for reconnaissance :

Orders are issued by the General Staff to the
wing commander, who in turn issues orders to
the squadron commander, who in turn may issue
them to the flight commander.

The orders by the general staff usually ex-
plain the general situation and so much of the
commander's intention as it may be necessary
for observers to know in order that they may un-
dei-stand the objects of the reconnaissance.

The information which the commander re-
quires is definitely stated, and the best results
are obtained if the information is asked for in
question form.

The orders of the wing commander and other
officers usually include:

(a) Information as to the enenw and of our
own advanced troops.

(b) The object of the reconnaissance.

(c) Route to be followed if general informa-
tion is required. (If certain definite informa-
tion is required, the route should not be given.)

(d) Special points to be watched for.

(e) Time of starting if necessaiy.

(f) Method of reporting and where to send
messages.

(g) Procedure to be adopted in case of
breakdown.

(h) What other aircraft are reconnoitring

Balloons were the first type
of aircraft to be used for ob-
servation. An early artist's
interpretation of the employ-
ment of eaptive balloons by
the French at the Bafth- of
Flcunis, June 26, 179+. Being
thus su])plied witli "aerial
eyes" tlie French had tlie ad-
vantage over the Austrian ar-
mies.

RECONNAISSANCE AND CONTACT PATROL WORK -

113

The change forced by aerial observers. This
shows a lieavy French gun in 1914^15. It was
not protected from the aerial eyes.

the same objective or on the flanks of the route
detailed.

(i) Number and type of fighting aeroplanes
assigned to guard and protect the observer, if
any are so assigned.

All orders and instructions should be in writ-
mg, except in very special circumstances.
They must be given as early as possible in order
to allow the pilots time to study their course,
plot compass bearings, etc.

Squadron and detached flight commanders
keep a record of the general situation, so as to
enable them to give pilots any information they
may require before starting on a reconnaissance.
The best method of keeping this record is by
means of maps marked with colored flags.

Full information as to the general situation
should be given to the pilots and observers, and
they should study the map kept up by the
squadron commander in order that, in the event
of their discovering some unexpected informa-
tion, they may be able to decide whether it is of
such importance as to justify them giving up
their original mission and returning at once.
As a general rule, however, when an aircraft is
given a definite route to follow or a definite ob-
jective to discover, it must complete its mission.

General information of importance regarding
procedure, signaling map used by observers,
etc., can be found in the chapters on "Directing
Artillery Fire" and "Areas Photography."
Detailed information regarding scientific instru-

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This shows a heavy French gun in 1917, pro-
tected from the aerial eyes by a cover of cloth,
branches of trees, and other devices that are
part of the art of camouflage.

114

TEXTBOOK OF MILITARY AERONAUTICS

A dummy gun half hidden by trees to mislead the enemy aerial observers.

ments can be found in the "Textbook of Naval
Aeronautics," also published by the Century
Co., X. Y.

How Reconnaissance Aeroplanes Are
Guarded and Protected

• The protection afforded the pilots and ob-
server is naturally of great importance. The
danger to the reconnaissance machines comes
from: (l) Attacks by enemy fighting aero-
planes, (2) Anti-aircraft guns. Against the
latter aviators can only protect themselves by
gaining information of their location whenever
possible from other aviators, and by manoeuver-
ing their airoplanes to dodge shots. Against
the former there are two methods of protection :
(1) By using larger and more powerful aero-
planes, capable of carrying two or three men
and from two to four guns, thereby permitting
each aeroplane to defend itself ; (2) By sending
with the reconnaissance patrol a guard of fight-
ing machines to protect them from attacks.

The former is becoming more and more popu-
lar, because it makes every aeroplane self-pro-
tecting and eliminates the possibility of recon-
naissance aeroplanes being brought down by a
lonely enemy machine which can dive down on a
helpless reconnaissance machine, shoot the pilot,
and land before the protecting machines can act.

As the fight takes place over the enemy's lines,
the fighting machines cannot follow the enemy
machines in their downward flight without ex-
posing themselves to the fire of the anti-aircraft
guns. Three men in a machine equipped with
dual controls and several guns can withstand
the attack of any machine or of several ma-
chines, and one of the three is usually able to fly
the machine back to his line, whereas in a single
or two-passenger machine the loss of one man
often leads to the loss of the other man and the
machine.

The first duty of the fighting reconnaissance
machines is to gain information and get back
with it. They do not go out with the intent to
fight, but must be capable of doing so, since
fighting is often necessary to enable them to
obtain the required information. With two-
seaters, the pilot operates the machine and the
observer carries out the reconnaissance, and both
operate the guns if necessary. In three-seaters
the pilot operates the machine, the observer car-
ries out the reconnaissance, and the third man
watches for enemy machines. It is best for all
three to know how to pilot the machine and op-
erate the guns.

Reconnaissance machines are seldom called
upon to act alone, but fly in formation, one or
more machines carrying out the reconnaissance,
while the remainder act as escort, on the same

RECONNAISSANCE AND CONTACT PATROL WORK

115

principle as an escort on the ground. That is to
say, they do not seek an engagement, but fight if
necessary, to enable the reconnaissance machines
to do their work. See chapter on "Fighting
Planes and Aircraft Guns."

Protecting Reconnaissance Machines

In protecting reconnaissance machines from
attacks, important use may be made of the di-
rections which have been supplied to the person-
nel of reconnaissance machines of different coun-
tries. These directions have been found on cap-
tured flight commanders or pilots, and should
therefore be carefully examined by students.

In reconnaissance, the whole object is to pro-
tect the reconnaissance machine or machines, and
enable them to complete their work. Opposi-
tion will usually take one of two forms. The
enemy's scouts may employ guerilla tactics,
hanging on the flanks and rear of the formation,
ready to cut off stragglers, or attacking from
several directions simultaneously, or else the
formation may be attacked by a hostile forma-
tion. A suitable type of two-seater fighting
reconnaissance machine will often be able to

deal with either class of opposition without as-
sistance. The machines must fly in close for-
mation, keep off enemy scouts which employ
guerilla tactics by long-range fire, and be ready
to attack a hostile formation, if the enemy's
opposition takes that form.

Reconnaissance formations, like fighting for-
mations, can be organized in groups, each with
its sub-leader, but as the object is to secure the
safety of the reconnaissance machine, the whole
formation must keep together and act as one.

If scouts are used in combination with two-
seater machines on a reconnaissance, it is usually
preferable to keep the two types of machines
as distinct formations, each under a separate
leader. The two-seaters act as described, and
the scouts fly above them in such a position
as to obtain the best view of them and the great-
est freedom of manoeuver in any direction.
Their role is :

( 1 ) To break up an opposing formation.

( 2 ) To prevent the concentration of superior
force on any part of the reconnaissance forma-
tion.

(3) To assist any machine which loses forma-
tion through engine or any other trouble.

A fake battery planted to deceive the aerial observer.

116

TEXTBOOK OF MILITARY AERONAUTICS

Gothu bombing acroi)lane brought down in Belgium while returning from u rail un Englcuul.

Navigation Rules for Reconnaissance

The height at which aircraft will fly during
reconnaissance is governed by the state of the
atmosphere and the consequent ease of observa-
tion. The duty of gaining information must be
the primary consideration, and aircraft person-
nel must always be prepared to expose them-
selves to hostile fire if they cannot otherwise
carry out efficient obsen^ation.

The difficulty of replacing trained personnel
and aeronautical material must, however, always
be borne in mind.

Shells of the big guns hiildtn trmn the aerial observer's eyes.

Once obtained, information must he delivered
at headquarters as safely and rapidly as pos-
sible. Consequently, aircraft retin-ning from
reconnaissances should fly at such a height as to
render them absolutely immune from fire from
the ground.

The chances of being hit from the ground will
be diminished by following an imeven course
both in direction and elevation. Advantage
may also be taken of cloud for concealment.

The action to be taken against hostile aircraft
will vary according to the mission which the
pilot has been given.

Should he have been despatched to clear up
some important point, or should he be retm-n-
ing with valuable information, he must be care-
ful to concentrate his energies on avoiding hos-
tile aircraft.

If, on the other hand, having seen nothing, he
should neet a hostile aircraft over or near a
place where it is obvious that it must have
gained valuable information, he must attack it.

It must be borne in mind that the side whose
aircraft show the greater determination to fight
on every opportimity Avill rapidly gain a moral
ascendancy which will largely contribute to ob-
taining the command of the air.

Pilots and Observers

In order that good results may be obtained
from aerial reconnaissance, the same |)ilot
and observer should Avork together as far as
possible. Mutual confidence is of the utmost
importance.

It has been found inadvisable to lav down any

RECONNAISSANCE AND CONTACT PATROL WORK

117

rules as to the respective duties of pilots and ob-
servers. These must depend largely upon the
personality and air experience of the indi-
viduals. On receipt of orders, the pilot and ob-
server should consult together with the aid of a
map as to the best manner of fulfilling their task
and the route to be followed.

Compass bearings, distances, and times must
be worked out, and, if necessary, tabulated and
fixed to the machine, so as to be clearly visible
during flight. Allowance must be made for the
probable drift due to the wind at the height at
which the aeroplane will fly.

The pilot is responsible that his machine, if in
flying order, is ready to go up whenever re-
quired. Before starting, he must test his en-
gine, verify the quantity of oil and petrol in his
tanks, and make a final inspection of the ma-
chine with his mechanics.

He marks the route on his map and places it
in readiness.

The observer also marks his map, and in cer-
tain cases, when a detailed reconnaissance is re-
quired, makes an enlargement of it and dupli-
cates it with the aid of carbon paper. He pre-
pares his apparatus, notebook or writing block,
pencils, weighted message bags, watch, field-
glasses and, in some cases, a camera.

No person going up in an aircraft should
carry written matter or maps which, in the event
of an accident, would be found on him and give
information to the enemy.

The responsibility of finding the way must be
shared by the pilot and the observer; the actual
method of navigation adopted depends on the
nature of the country, the state of the weather,
and the type of aeroplane used.

The pilot will conform to the direction of the
observer as regards moving slightly to right or
left, so as to gain a clearer view of a road, cir-
cling round so as to examine a place more thor-
oughly, or coming lower down to get a clearer
view.

The pilot should assist in observation by look-
ing out on the opposite side to the observer.

Observers must be constantly on the look out
for information both on the way out or returning
from their reconnaissance ; and, though they may
have accomplished the tasks specifically allotted

To deceive the aerial enemy's observers the art of camouflage
is applied to men as well as machines- The crew of a French
antiaircraft gun dressed with a view to invisibility.

to them, they must not consider their duty
finished.

In addition to using a speaking tube, a simple
code of signals should be arranged so that the
observer can communicate his wishes to the pilot
without the latter having to switch off or throttle
down his engine.

In the case of a forced landing inside the
enemy's lines, when it is evident that the machine
must be captured, the pilot is responsible for
taking such steps as will render it useless to the
enemy; setting fire to it will generally be the
most effective method.

The pilot will assist the observer in making
out his report. All reports will be signed by the
observer.

Messages should be written out fully in the
recognized manner, headings being as far as
possible filled in before leaving the ground. It
must be remembered that the omission of any of
the usual headings will reduce the value of a re-
port or may even render it useless.

The positions of troops on the ground, espe-
ciallj^ when they are scattered, can often be most
easily explained by showing them on a carbon
tracing or enlargement of the map. A rough
diagram will frequently be of great value in

118

TEXTBOOK OF MILITARY AERONAUTICS

■uiwi I. . J immmimim

i!xm>fiim<mam^.''»it-:m!9!?MVi^'''

Directing a movement of troops by aeroplane.

elucidating the exact meaning of a written
message.

Facts only are to be reported ; it is the duty of
the staff to which the report is sent to make the
deductions. For instance, the positions of the
head and tail of a column at given times should
be stated and not merely its deduced strength.

An observer will always report if he is in any

The Sopwlth tractor biplane, widely used in tlic war w>ne.

doubt regarding the reliability of his observa-
tions.

In cases when an aircraft has been out for
some hours and seen a number of small details,
it is advisable to add the general impression
formed by the observer as a result of what he has
seen, but it must be made quite clear that this is
merely an opinion and not necessarily a fact.

It is of great importance that reports from
aerial observers should reach their destination as
soon as possible. INIuch of the value of aerial
reconnaissance will be lost if the information so
quickly gained is delayed in transmission to
headquarters.

Aircraft Report Diary

An aircraft report diary should be kept in
each scpiadron or detaclicd fliglit.

A summary of the information collected

IIECONNAISSANCE AND CONTACT PATROL WORK

119

A Russian air scout operating under difficult conditions.

should be made out daily and sent to the head-
quarters concerned, to prevent the possibility of
any message having been overlooked or having
gone astray without the knowledge of those
concerned.

Contact Patrol (Aeroplanes De Liason)

The contact patrol, which came in the year
1916, is one of the latest developments in mih-
tary science. Established at first as a con-
venience, it is now a distinct service of extraor-
dinary importance, and binds together the aerial
and land forces.

As a writer pointed out in Aerial Age
Weekly recently, Contact Patrol, which is one
of the chief raisons d'etre of the aeroplane, is a
special tactical reconnaissance carried out dur-
ing the progress of an attack. It establishes a
liaison between the front line infantry and their
battalion headquarters, corps, or division head-
quarters in the rear. The aeroplane is the most
valuable means of connection, and accomplishes
the following objects:

(a nnderwood &, Underwood
Remarkable photo of a French Spad Chaser plane, taken from above, under great difficulties.

120

TEXTBOOK OF MILITARY AERONAUTICS

One of the Hrrjfuct homWmii tyiM- bipliinrs used by the French, which arc most rcinarkuble clhiibers, thouL'h they arc limited in the
load they ean carry. I'nfortunately the Germans have hroiiirht down several of this tyi>c and will be able to copy it.

(French Official Photo.)

RECONNAISSANCE AND CONTACT PATROL WORK

121

A Farraan reconnaissance biplane passing another reconnaissance
machine.

1. Keeps higher command informed of own
troops' movements.

2. Keeps higher command informed of en-
emy troop movements.

3. Carries messages from battahon headquar-
ters to corps and division headquarters.

4. Reports the state of enemy trenches dur-
ing an attack, and also reports any new enemy
trenches.

There are four methods of signaling from
the ground to an aeroplane engaged in contact
patrol. They are:

1. Ground strips. This method consists in
white strips of cloth which are placed on the
ground in various shapes according to prear-
ranged code. Thus, a ground strip in the shape
of a "T" might mean "Need Ammunition," or
some similar message.

2. Signal Lamps. These are colored lamps
with a special slide which pennits light to ap-
pear in flashes, long and short, and the mes-
sages are sent according to the Morse Code, or
some other prearranged code.

3. The Shutter. The shutter is a device very
similar to the ordinary window bhnd, with one
side of each shutter painted white and the other
side black. It is operated by a cord, and the
code used is generally the INIorse International.

4. Flares. These, as the name suggests, are
simply oil-soaked cloths which are lighted by the
front line troops to show their position during
the attack.

On sunny days the method most used is the
panel, but on dull days the lamp is used. Gen-
erally an infantry battalion has either the lamp
or the panel (Shutter), sometimes both. The
battalion headquarters always has both. All
messages are sent from battalion headquarters.

The following are the methods used by the
aeroplane to communicate with headquarters:
1. Wireless. 2. Signaling Lamp. 3. Klaxon
Horn. 4. Skeleton maps, and messages
dropped in weighted message bags. In some
brigades, by Very's lights and smoke bombs.
In the Very's light method a red and green
flare are used, and the succession in which they
are fired indicates the message. Wireless is
very rarely used in contact patrol work, and is
never used to refer to the position of our own
troops, as the code might be intercepted by the
enemy very easily.

As our own barrage fire is regulated by the
aeroplanes on contact patrol, the pilot of the
aeroplane must be absolutely certain that the
troops signaling they are the first line are the
first line, as a mistake would place them di-
rectly vmder their own barrage from the rear.
Thus in very doubtful cases the aeroplane flies
so low that the pilot recognizes the uniforms of
our own troops. This, of course, makes the

A "protecting" Xieuport fighting biplane photographed by the
observer of a reconnaissance machine.

122

TEXTBOOK OF MILITARY AERONAUTICS

A two seater Morane-Laulnier contact patrol machine.

work very dangerous. The procedure of con-
tact patrol work during an attack is as follows :
The hour for the attack is known as the "Zero
Hour," and all watches and time pieces are care-
fully set to coincide to the second. Exactly
at the Zero Hour the aeroplane must arrive over
the front line trenches, in such a position to be
over, or imder the expected barrage, generally
just over it, at a height of 1500 to 2500 feet.
The pilot watches the attack until the infantry

reaches its first objective, then signals "Where
are you?" by one of the methods described
above. The infantry, in response, lights a flare
to show their position, and the pilot traces it on
a skeleton map, and flies directly back to head-
quarters. Arriving at this position, he places
the map in a weighted message bag, together
with any other message he wishes to send, and,
coming down to an altitude of about 200 feet,
drops the bag. If the ground does not acknowl-

. ^^ 1

>i^K ^^>flHK; i4|H

1 - ll>>^ii.i.^

■iB^Bii

An Allii-d /,c|i|)flin <liii»i-r wliirh <iirrii-s a timclimi- (.niii iiiiiiiiilrd ill fridit of lilt- car, anil alta<ln(l to Oir frame work arc a iicrics
of ruclcctH, and Ix-low tho lower wings a battery of searchlights. Note the rockets for setting Zejipelins on Are.

RECONNAISSANCE AND CONTACT PATROL WORK

128

A squa

c;ioii ui

N .c

edge the message in two minutes, he drops an-
other, and keeps this up until his message is
received and acknowledged.

An example of the great covu-age often dis-
played in this branch of work was shown during
an attack on Dead JNIan's Hill bv the French

)iUn used for special contact patrol work.

Infantry. As is well known, this hill has passed
back and forth many times, and some of the
fiercest fighting of the war has taken place on
its slopes. During this particular attack the
pilot of the aeroplane engaged on contact pa-
trol wished to make no mistake, so, descending

French pursuit machine being prepared for a flight over the enemy's lines. (French official photo.)

124

TEXTBOOK OF MILITARY AERONAUTICS

under his own barrage, to a height of about
100 feet, he flew directly over the heads of his
own troop, and hterally climbed the hill with
them!

Contact patrol is thought to be the most dan-
gerous of all the various usages of the aeroplane
at the front, and requires a man not only of
unquestioned courage, but of great judgment.
It is the connecting link between the man in the
trench and the man directing the attack, and as
such must at all times give accurate informa-
tion, as one mistake may mean the loss of thou-
sands of hves. It is a work without the glory

of the aerial fighter in his scout machine, miles
above the earth, but is vitally important to the
success of an attack. In an attack, in addition
to doing his work, the pilot has five forces to
contend with. They are: His own barrage, the
enemy's barrage, anti-aircraft guns, enemy ma-
chine guns, and enemy aeroplanes. Thus it can
be seen that a pilot who flies up and down the
lines in a straight line invites destruction. So
the pilot must know the trajectory of the heavy
guns being used in the barrage, so as to keep
above or below it, he must never fly in straight
lines, or continue always at the same speed.

Memoranda:

A patrolling French aeroplane signalinfr with searchlight above darkened Paris. This remarkable photograph was taken from the
Church St. Gervais looking toward Notre Dame (on the right) and the Pantheon (on the left).

CHAPTER X
NIGHT FLYING

Since practically all offensive aeronautic
work is now done under cover of darkness night
flying is one of the essential things an aviator
must learn.

Zeppelin Raids Forced Aeroplane Night
Flying

The night Zeppelin raids forced aeroplane
night flying on a large scale. The Allies were
forced to establish night aeroplane patrols by
public opinion, which seemed to take for
granted that a few aeroplanes in the sky would
be able to prevent Zeppelins from cariying out
their work of destruction. Public demand had
to be met, notwithstanding the fact that no one
coidd say just how the aviators were to go up
at night, whether they could see other aircraft
traveling in the dark sky, how they could main-
tain their machines on an even keel, how they
were to return to their starting-place and land
against the wind, etc.

Long-Distance Bombing Night Raids

Long-distance bombing raids are conducted
entirely at night. During the day the anti-
aircraft guns and enemy aeroplanes combine in

125

preventing successful results. At night neither
the anti-aircraft guns nor the aeroplanes are ef-
fective. With few exceptions, therefore, raids
are conducted at night, unless there are trains
loaded with troops or supplies to be destroyed,
or something of a pressing nature to be bombed.

Aeroplanes Cannot Be Seen One Hundred
Feet Away

At night aeroplanes cannot be seen one
hundred feet away, and it is difficult for the
searchlights to "pick them up." Dirigibles can
be picked up with comparative ease. The in-
visibility of aeroplanes at night is illustrated by
an experience at Salonika. An Allied aero-
squadron started out one night to bomb the
Turkish-German positions. On arriving at a
point above the German lines the bombing
party was surprised to see the Germans light up
their aerodrome. They took advantage of the
opportunity and dropped their bombs on the
hangars and other buildings. When they re-
turned to their own lines they found that the
Germans had meanwhile bombed the Allies'
aerodromes. Both forces had planned bomb-
ing raids at the same time to surprise the other
side. The bombing squadrons passed each

126

TEXTBOOK OF MILITARY AERONAUTICS

A Zeppelin over London at night.

other on the way, but without observing one an-
other. In each case the officers in charge of the
aerodromes, upon hearing the noise of aero-
plane motors, thought it was the noise of their
own aircraft returning and lit up their aero-
drome to enable them to land.

The Operation of Aeroplanes by Night

While the navigation of airships by night is
a comparatively simple matter, such is not the
case with the aeroplane, which cannot stop in
mid-air for the purpose of inspecting the ground
beneath. And, whereas an aeroplane lands
with a velocity of seldom less than forty miles
per hour, it is imperative, if aeroplanes are re-
quired to fly by night, to provide adequate land-
ing and navigating facilities.

First, the aviator must know his relative posi-

tion to the ground. For this purpose the ma-
chine must be fitted with an altimeter, for indi-
cating the height, an inclinometer for indicat-
ing the aeroplane's inclination, and finally, posi-
tion lights showing the transverse position of the
wings. The latter requirement is attained by
small electric bulbs (colored blue so as not to
blind the pilot nor reveal his presence to the
enemy) which are fixed on both wing-tips; the
current is furnished by a storage battery, which
is also used for lighting the blue lam})s which
permit reading the navigating instruments.

The same battery may, furthermore, be used
for working a small searchlight, with the help
of which the pilot might hope to effect a land-
ing if forced down by engine trouble. The use
of searchlights, however, has not been general
on aeroplanes. Since it might reveal the avia-

NIGHT FLYING

127

French aviator about to start on "Zeppelin Duty" at niglit, the searchhght being temporarily turned on the machine.

tor's presence to the enemy, it is now used ex-
tensively for landings.

The second and principal requirement for
night flying — assuming the engine to be of a
reliable kind — consists in providing adequately
lighted landing-stations.

Lighting the Aerodromes

The principle governing the lighting of aero-
dromes for night landing consists in suppressing
all light that might bhnd the aviator, and only
using such as will make the ground appear clear
enough for recognition. Numerous systems of
lighting aerodromes have been tried, and new
methods are being experimented with con-
tinually. The first method employed was the
use of petrol flares, which are nothing more
than buckets of petrol set on fire. This method
is still in use, but it is essentially a makeshift,
being both dangerous and expensive.

The use of electric lights affords the greatest
efficiency, at the same time making it possible
to turn all the lights on or off simultaneously.
The lights, whether flares or electric lights, are

placed so that when lit they form from the
aviator's position a wide arrow, which points
into the wind. The aviator lands in the wide
part of the arrow, and since the aeroplane pro-
ceeds toward the point, he flies into the Avind.

In a recent article in "London Aeronautics,"
a writer gives interesting information on night
flying, with special regard to conditions ob-
taining in England and in France, as fol-
lows:

"The conditions of night flying in England
and in France are vastly different: in many in-
stances pilots fresh from England have had no
previous experience in it, while others who have
flown a lot are not up to the same flying stand-
ard as those who are initiated out there. Any-
way, they all require a lot of practice from a
military viewpoint.

"Individual opinions often differ as to the
merits of particular machines, and it is not often
that one gets such a unanimity of view as is ex-
pressed in favor of a certain type in regard to
its nocturnal qualities. It makes an excellent
night flier and — more important — night lander;

Powerful searchlight for illuminating hangars.

Searchlignt illuminating landing ground.

128

TEXTBOOK OF MILITARY AEROXAUTICS

French aeroplane for night operations showinjir the searchlight on the machine and small lights under the bottom wing.

General Pershing is visiting French aviation camp.

pilots with verj'^ little, or sometimes no experi-
ence in this art of flying invariably make good
landings on these machines. Xatiirally, pilots
with insufficient experience are not permitted to
take up observers to fill the passenger's seat, and
consequently ballast is required to give the ma-
chine longitudinal stability. This type, being
perhaps the most successfully designated of the
R. A. F. productions, is extremely tail heavy
without its full complement, and even with 100
lbs., is still light; pilots will find that 135 lbs.
weight will give the best results and will eradi-
cate any jerky tendency should the engine suf-
fer from 'variable pull' — in fact, the machine
has been safely flown 'hands off".'

"While on the subject of landing, it is inter-
esting to note that the French have an excellent
landing system, very similar to our own, which
has been extensively used during the recent and
present Verdun operations. Barring unfortu-
nate contingencies, French machines are not
permitted to land until they get the signal 'AH
clear' from below. When a French pilot ar-
rives over what he thinks is his own aerodrome,
he circles around, .sending his own special letter

in IMorse by searchlight; this should be answered
by one of the ground projectors, and a machine
should never land until the call has been an-
swered, the main idea being to prevent machines
landing on hostile aerodromes or even on those
of neighboring squadrons.

"The method in use in British squadrons is
for a pilot on approaching an aerodrome, and
wishing to descend, to fire one of his Very
lights. The predetermined signal will be an-
swered from the ground. If the signals agree,
the pilot will know he is over his own drome and
may accordingly land. If the signals do not
agree, he will recognize from the color of the
ground the signal of the aerodrome he is over.
As every pilot should memorize the signals of
adjacent aerodromes, this method will also as-
sist him in determining his course for his own
aerodrome. The distribution of landing flares
is on the foHowing .system:

Three flares in line, so 0

One flare in the R. H 1

bottom corner, so

NIGHT FLYING

129

"A pilot wishing to descend should know
by prearrangement which of these flares are
doubled so. There is a different one in each
brigade. The vai'ious aerodromes and land-
ing stations in a brigade are distinguished by
the color of the Very lights fired from a spot
adjacent to the double flare. Owing to mili-
tary exigency, it is impossible to state more
plainly the code on which this is based.

"Flare lighting is controlled by the Brigade
Headquarters. They are lighted on receipt of
orders, and are kept going until ordered out.
At its discretion a Brigade Headquarters may
request a neighboring aerodi'ome to 'flai'e up.'
Pilots flying at night are individually responsi-
ble for informing their Brigade Headquarters
of their safe atterrisage.

"Night flying is dependent largely upon the
weather, but for our purpose can be divided into
two categories — moonlight nights and other-
wise. When conditions are good, and the moon
bright, perfect night flying can be practised and
observations taken easily up to a height of 9000
ft.; landing grounds and aerodromes can be
seen quite plainly at this height, although on
ascent the machine is quickly lost to view from
below. So difficult is it to spot machines at
night, unless carrying distinguishing lights, that

Aeroplane searchlight mounted on a biplane. The search-
light, 500-watt power, is operated by a wind-wheel and has no
connection with the aeroplane motor. It is designed to be used
as a signal light and to aid in making landings at night.

a hostile machine over the lines on one occasion
could neither be seen from the ground nor the
air. On occasions when our machines pene-
trate over the lines the enemy guns cease
firing, presumably so that gun-flashes shall
not be spotted. Under the most perfect
conditions railways are difficult to see, but
sometimes a train may be recognized by its white
smoke.

"With no moon, at 5000 ft., it is not possible
to distinguish railways, roads, or rivers; but
aerodrome flares are quite effective at this

u i.

— "^ni^^^^H

jjjj^

"l"''''^^^, %\

ifKI^ ^^^I^^^^^^B

■'■:^^^^&::00M.'^mM

German aeroplanes at a German aerodrome at night.

130

TEXTBOOK OF MILITARY AERONAUTICS

A Taube at dusk.

height — in short, on moonless nights only lights
can be seen. Even on "moony" nights, at 2000
ft. unlighted objects cannot be seen with any
certainty on the road ; yet at 7000 ft. on an ideal
night, roads are clearly seen looking vertically
down, and lighted motor transports are easily
discernible. Villages and towns are also "on
view"; the British trenches may also be seen
with the aid of flares.

"The danger of keeping aerodromes 'flared'
while machines are out on reconnaissance re-
sults sometimes in hostile machines (which can-
not be placed) dropping bombs.

"We have by no means reached finality in the
design either of parachute flares or wing-tip
flares. Of two parachutes tried recently, only
one burned, while the other flare, on exam-
ination, was found to be only partially burned ;
the latter flare ignited, burned steadily for a
short time, and then went out, with half the

composition unburned. This is extremely
dangerous, as it leaves the pilot in the dark just
at the moment of landing, when he most needs
the light. The arm of the flare is apparently
too weak, and becomes bent in the course
of flying. If bent so as to bring the flare
close to the wing, it should work satisfactor-

ily.

"In view of the landing difficulty, the sugges-
tion that every aerodrome should be equipped
with a portable projector is excellent. Pro-
vided the jjilot is always able to land head on to
wind, the beam remains pointed to windward.
Great care must be taken to keep the beam sta-
tionary, as any glare in a pilot's eyes would blind
him and have unfortunate results.

"A closing hint to flight and squadron com-
manders might not be out of place here.

"Pilots detailed for night flying should have
plenty of opportunity to practise on the same
machines vith which they will fly at night, and
should be instructed to practise the following
operations :

• •>••■.••'..'.■■.-.

.'iJ^'J'^...'.'

'->-

Cross-sectional view of one of flie new German
aviation iK-acons

Couneay acientiflc AmtrUxm

NIGHT FLYING

131

Lighting stand, serving the double purpose of guiding nocturnal flyers to a safe landing and detecting hostile aeroplanes.

-I.e.

with-

1. Flying by instruments alone-
out using the horizon as a guide,

2. Gliding slowly.

3. Making small sideslips and quick recov-
eries.

4. Checking the speed of the machine and
identifying it with the sound of the wires under
certain conditions.

5. Turning, using instruments alone,

6. Landing slowly."

The "Honig Circles" Signals for Night
Flyers

The ingenious arrangement of signals for
night fliers, patented by the German architect
Edgar Honig, was described in the Technische
Monatsnefte and translated in the Literary Di-
gest. The apparatus consists of two concentric
circles or rings of incandescent lamps standing
on edge a few feet from the ground, with the
smaller one placed at a distance of several yards
behind the larger one, which stands back of the
landing stage.

The working of this arrangement depends on
the wellknown fact that a circle appears as an
ellipse as soon as the eye ceases to be directly
opposite the center. Hence two circles of light,
arranged as Figure 1, must be perceived as two

upright or slanting ellipses which either inter-
sect each other or have the smaller contained in
the larger, until the eye of the beholder is directly
in line with the axis passing through the middle
point of the two circles. In the case of the

X'hotograph of the IliiTiig Circle.^.

:^";5

132

TEXTBOOK O^ MILITARY AERONAUTICS

i. — From above, the aviator
sees two ellipses only.

3. — As he descends, the
circles round out and cut
each other.

Honig Signal Circles
whose central axis
stands about 13 feet
above ground, this occurs when the airman is
from two to three feet (according to the build
of the machine) above the ground.

Figure 2 shows how the circles appear to a
flier who finds himself at a great height above
the signal and flies directly down in the direc-
tion of the central axis of the circles. When he
comes farther down, probably flying in a spiral
and thus nearing tbe ground, the rings begin to
intersect, and appear to him, for instance, as in
Figure 3. This position of the light-circles re-
veals to him not only that he has approached the
earth, but also that he has diverged from the di-
rection of the middle axis, and that he must
steer his machine to the right in order to obtain

-"Earth level! Steer
left!"

5. — ■'"Home !"

the right direction again. He does this, still
continuing to descend until he sees the signal,
perhaps as in Figure 4. He knows then that
he has approached the level of the ground.
Consequently he steers, and the operation con-
sists merely of turning on the current when a
machine is heard approaching at night, in cases
where the lights are not needed to bum con-
tinuously. Where the signal is part of the
equipment of an aviation corps in an army, it is
easily arranged so that the rings can be fastened
together and transported without difficulty
when camp is changed. The invention is like-
wise specially valuable for water landings.

Lights for Night Landing Grounds

Mr. Bright the British authority in his report
on the best lights for night landing grounds
says in this connection: "While undoubtedly the

I. — How the. circles of light guide the night-
fliers. The relative positions of the two con-
centric light-circles reveal to the aviators, as
the dotted lines show (and as the diiigranis of
the opposite page indicate), their angle of
approach to the aviation-ground. See article
on next page.

NIGHT FLYING

133

light obtained from the ordinary petrol flare is
better suited for the purpose than the white light
from a conmion arc lamp, the same does not ap-
ply in the case of the comparatively new flame
arc lamps which are recommended for this pur-
pose. The value of the petrol flare was settled
as far back as 1885 when the South Foreland
experiments were conducted at the instance of
Trinity House (see "Report of the Committee
on Experiments at South Foreland relative to
Electricity, Gas, and Oil as Lighthouse Illumi-
nants") . The new flame arc lamps give a yel-
low red arc when the carbons are made in a
manner separately communicated. Indeed, the
light produced by the yellow flame carbon has
the highest penetrating power of any known il-
luminant, and has great advantages over all
others (including petrol flares) in foggy or hazy
weather. The light obtained from these special
flame arc lamps (fitted with yellow flame car-
bons) is very near in color to petrol flares, but
is considerably more powerful. A further im-
portant advantage in an electric lighting system
of the special type named would be that, unlike
petrol flares, all the lights can be simultaneously
switched on and off at a moment's notice."

Returning from Night Flights — The Signals

To the aviator engaged in long-distance night
raids night flying still holds difficulties to be sur-

A convenient French aerial beacon.

Portable aerial beacon of 2400 decimal C.P.

mounted. There. are a few difficulties however,
confronting the aviator on "Zep duty" who does
not venture far from his base. The long dis-
tance raider may lose his way in the darkness;
the aviator on "Zep duty" only has to flash the
signals, and since the landing stations in Great
Britain and France are numerous, the signal is
usually answered by one of the stations lighting
up so that the aviator may land.

Naturally, the signals are changed daily.
The authorities issue daily signals and the me-
chanics load the signal pistols accordingly for
the aviators. The lights or flares can be seen
from a distance of from ten to fifteen miles.
Aeroplanes are also equipped with lights placed
beneath the bottom wings and with automobile
lamps so that in case of a forced landing they
may come down with little trouble. These
lights are turned down by pressing a button.

Lighting Equipment of Aeroplanes

The lighting equipment of aeroplanes varies
considerably. Following are the British Gov-

134

TEXTBOOK OF MILITARY AERONAUTICS

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ernment's specifications for the lighting equip-
ment of certain battleplanes and the passenger's
bay.

Electric lighting equipment. This will be
fixed in a suitable manner. Dry batteries of
the life of 4iA hours to be provided to light up
the dashboard. As the machine will not be fly-
ing for a longer period than 8 hours, the extra
dry battery provided can be used in emergency.
When these dry batteries are exhausted, they
can be thrown away. They weigh about 21 lbs.
each.

The lighting to be arranged as follows :

2. Lights to throw light on the instrument

board, and arranged so as not to throw it in the

pilot's eyes.

1. Light at the bottom of the fuselage, to
throw light on the floor in case the pilot wishes
to throw light there for any purpose. This is
also to be shaded so that it will not throw light
in his eyes.

1. Light for the compass, arranged in the
same way.

1. Portable torch to be provided with each
machine.

Instruments Painted with Luminous
Compounds

The instruments used by aviators in night
flying have the indicators and dials painted with
luminous compounds, which eliminate the blind-
ing glare of electricity and the necessity of using
flash lamps. The parts so painted can be seen
clearly by the pilot who for the time being is en-
tirely wrapped in darkness.

Aerial Lighthouses
It is as essential that air men have hghthouses
to guide them through the atmospheric ocean
as for navigators at sea. The aerial beacons
are of several types, the most powerful having a
candle-power of 50,000 and being visible for up-
ward of fifty miles. As the result of much ex-
perimenting a general type of beacon has been
developed. It consists of several belts of
lenses, with a powerful lamp at their focus which
sends out its rays uniformly in all directions.
It is necessary, of course, that the light be
clearly visible to the air man, whether flying
above or below the light. Each lighthouse
must have a distinctive mark of its own, so that
the air man will be in no danger of confusing
them and losing his way. A series of light-
flashes are thrown out, corresponding to the
dots and dashes of the JSIorse code. The air
man soon learns to read these signals, or to ver-
ify them by a code book, and can thus readily
learn his position, even when the earth beneath
him is completely hidden.

■ Adventures in Night Flying

Following is a letter from Lieut. Red. H.
Mulock, R. N., the Canadian pilot who was the
first to succeed in chasing a Zep at night, and
did so at a time when arrangements for signal-
ing between aeroplanes and aerodromes had
not yet been completed.

"Dear

"We have had a little fun around here. A

signal, indicated bjr dots and dashes, flashed from aerial lighthouses.

NIGHT FLYING

185

Showing the luminous tracks of three aeroplanes landing at night at a military aerodrome.

week ago, or rather Mondaj% the 17th, a Zep
blew along evidently looking for our aerodrome.
We heard him coming and presently saw him
flying in from the sea. I asked our C. O. if I
could go after him, and got away with some
bombs, grenades, and a revolver. He was steer-
ing a.bout due south, so I laid a course east of
south, and started to head him off. It was in
the middle of the night — a little after 1 a. m.
and no moon, very dark with clouds around and
the stars so dark you could not see the horizon.
He passed over here about 2,000 ft. up, and, by

the time he got to I was up even with him

and to seaward. I then changed my course
straight for him. He had stopped to drop his

bombs on and with his engine shut down,

heard me coming, and of course, as soon as he

heard me, looked in my direction and must have
seen the flames from my exhaust.

"Anyway he did not wait to throw anj^ more
bombs, and I saw the most wonderful sight. I
was about 1,500 ft. from him. He opened fire
with maxims, but without effect, and majestic-
ally stuck his nose up and went up like a balloon.
He was then higher than I, so I opened out

again, and tried to round him back again at ,

where we both turned out to sea and steered
about east. I chased him up to 8,000 ft. and
over to the Belgian coast, and we both changed
courses to S. E. and a little later went into the
clouds together over .

"Having lost him in the clouds, I climbed to
9,000 ft. and rambled around waiting for him.
But he had gone. There were two of them;

136

TEXTBOOK OF MILITARY AERONAUTICS

one was given a warm reception by the chaps

at , wliile the other one and I had a picnic

all to ourselves. He ran away so fast I could
not keep up with him and climb at the same
time. I waited around for him, but no Zep ap-
peared; evidently he stopped his engines and
listened for me, and then went off in another di-
rection. There was no use waiting, so I started
for home. I swung around out to sea from
coast, going north by compass. It was very
dark, and I could not see the sea or land and no
stars or moon, as I was in the clouds. Talk
about being alone in the world, very few people
know what it means. I came down to 7,500 ft.
and turned west finally, picking up some search-
lights in the distance. I thought they were at

and headed for them, and after some time.

three big searchlights jumped out of the dark-
ness below. Instantl}' I knew they were from
a cruiser and were looking for me, having heard
my engine. At night they fire on any one, as
they cannot see our large red circles. So, not
being particularly anxious to see how near they
could come, I started to dodge the large beams
and headed out north into the open sea again.

I worked my way gradually back to the

and later on saw the lightship, and then the

coast, which looked very dim way down below,
but it was home and once more I felt in the
world.

"I could not come down for two reasons.
First, it was not light enough to land and sec-
ondly, I knew I would be fired on if I w^ent
low. So I had to play around up in the sky
over the sea 7,500 ft. up waiting for the sun to
rise. As soon as it was light enough I came
down and every one seemed glad to see me back,
as they had given me up. I cannot begin to tell
you all about it, as one has to go through a night
like that to realize what wonderful things we
have. I enjoyed every minute of it, and every
minute Avas different.

"]My engine gave out once over the North
Sea but was able to keep her going slowly, and
finally as I was gliding down to the ocean for
some unknown reason, it picked up again. I
was going to glide for one of the searchlights
and land in the water alongside and be picked
up by a torpedo boat, but luck was with
me. Dodging searchlights over the North Sea
is the finest sport in the world. Funny, is n't
it, that we have to dodge our own guns
and lights? They cannot distinguish between
the Germans and ourselves, and take no chances,
so they fire on any engine they hear in the
sky."

Since the above was written arrangements
have been made for signaling between aero-
planes and the aerodromes. Lieut. William L.

German i>ortable gag beacon.

Aerial beacon with eicctric flashliglit.

Tlie aerial brnron at Johnnnistal, Germany.

NIGHT FLYING 187

Robinson who, on September 2d, 1916, brought airship fall, he looped the loop with joy, then,
down the first Zeppelin on British soil, in relat- "showed my signals to stop firing, and came
ing his exploit states that after seeing the huge down to earth."

Memoranda:

138

TEXTBOOK OF ^IILITARY AERONAUTICS

Fig. 9. Installation by German
government.

Fig. 11. A Zeppelin wireless outfit.

Fig. 12. A motor car wireless station.

Fig. 18. Airman's helmet with wireless re-
ceiver.

Aero wireless apparatus.
The use of wireless for communication be-
tween areoplanes and their bases has gradually
become more and more necessary and to-day
the aviators on all the fronts are equipped with
the most improved instruments available. For
every type of aircraft a suitable wireless set
has been developed.

Fig. 10. Large 5 K. W.
Zeppelin apparatus.

Fig. 19. Apparatus for seeing wire-
less signals.

Fig. 16. Early German Taube carrying wireless masts on

wings.

I'ig. 15. Wireless on 1913-14 monoplane used in I-'landcrs.

138

A double-motored Caudron biplane used extensively for observation, in France. It is equipped with a Lewis gun.

CHAPTER XI

RADIO FOR AEROPLANES

By William Dubilier

Unless one has made personal observations
as to the working of wireless and air craft in
this present war, it is difficult to appreciate how
the art of warfare has been transformed by these
two branches of science; and, in turn, modern

one day, and have been solved the next. One
incident may be mentioned where, in the early
months of the war, wireless stations were used
for directing the artillery. The shots from the
guns, however, were so constant and continuous

methods of fighting have changed the art of that they caused disturbances in the atmosphere,

radio and aeronautic engineering. Recent which, in turn, seemed to affect the receptor of

events and progress of wireless communications the wireless station, and so a continuous noise or

have established this branch of science as an in- click was heard, such as is produced by static,

dispensable means of transmitting intelligence Immediately physicists were set to work and this

from one place to another. objection removed, and so, many other problems

Radio and aeronautic communication may be in wireless have come up, as communication be-

termed the nervous systems of the army and came necessary under different conditions,

navy. Even for the directing of artillery fire
and communication between trenches, it has
been necessary to resort to electro-magnetic
waves from aeroplanes. Problems have arisen

which enlisted almost every radio and aero
worker in the fighting countries. They had no
time to try out new apparatus, except where
new conditions arose, and the instruments pre-

139

140

TEXTBOOK .OF MILITARY AERONAUTICS

U. S. Army biplane used in Capt.
Culver's experiments, siiowing radio
apparatus and aerials.

viously used were not suitable; so immediately
the departments were divided up into sections.
The practical men were set to work installing
and making stations as fast as the factories
could turn them out, and the experimenters and
physicists were ready to try out new apparatus
and rectify new objections.

Wireless and aeroplane companies in France,
England, and the other countries, except Ger-
many, were not so numerous or as large as they
are in this country, and so their output was soon
limited, which was much below the demand.
Everything obtainable was used for wireless.
The old type induction coils, apparatus which
was placed in the junk heap 10 years ago, all
became very handy, due to the fact that the

Virw of the e<xk-pit, sliowinjf nrrnntfcnient of the Culver set
which transmitted 119 miles.

Government was unable to obtain small sets,
and that the radio companies paid so little atten-
tion to this branch.

For this reason England subsidized many of
the large factories, such as the Sterling Tele-
phone Company, and devoted practically the
whole works to the manufacture of small radio
outfits of the aeroplane tyjje, under her own
supervision. In Europe, as well as in this coun-
try, development in that direction had been very
badly neglected up to the time of the war. All
acquainted with the present conditions on the
other side will admit that wireless and aero-
nautics is one of the most important assets, if
not the most important, and it is the small radio
outfit and the rapid machines which are making
it so essential. I hope this Government and
radio engineers in this country, will take ad-
vantage of this experience.

In all the small-power and portable instru-
ments used, whether they were the old appa-
ratus or the newly designed ones, the transmis-
sion has been in musical notes, and the spai-k-
gap in every case was of a quenched type.
Even in the 30- and -iO-watt instruments, using
a T2-volt storage battery with an ordinary in-
duction coil, quenched gaps were installed.
The copper discs were ll/4 inches in diameter,
14 i"ch thick, with a sparking surface of about
% sq. in., and small mica rings for separators.

At first the wire telephone and telegraph were
used everywhere, especially between trenches,
but very frequently the wires were broken by
shrapnel shell, and by the men themselves at
iiigiit, for that is the only time when they dare

RADIO FOR AEROPLANES

141

leave the trenches, and there is little possibility
to repair the damage. So wireless has proven
to be the only uniform and trustworthy means
of communication. Especially has it shown its
usefulness to the flying machine, for almost
every shot fired from the artillery is directed by
wireless from an aeroplane, which is constantly
flj'ing over the battlefield, observing the shots
and immediately signaling back if they landed
too far or too near.

Both the Central Powers and the Allies have
been using wireless trench sets. These must be
transported and operated by one or two men.
The transmission need not be more than five
miles, but the aerials must be very low, and the
instnmient must be robust and adapted for
rough usage. Several such instruments are
now being supplied, the highest and smallest of
this type weighing less than ten lbs. for the
transmitter, under five lbs. for the receptor, and
just over ten lbs. for the battery.

For aeroplane use great developments have
taken place in the design of the instruments.

Two types are mostly being used by the Eng-
lish and French Armies ; one having a power of
between 40 watts and less and the other 1.50
watts. Recently installations have been made
on the large aeroplanes built for England, the
details of which cannot be made public.

In supplying wireless apparatus for aero-
planes, light weight and compactness are the
most important requirements. The efficiency
of the instrument is no longer measured by the
power input to the power output. It is the dis-
tance to the weight, after considering reliability
of action. To cite an example: it is interesting
to note that the installation on almost all the
aeroplanes used by the French Government is
a very small and compact instrument in which
old principles were revived, the same as used in
first Marconi and Hertz experiments. There
are no tuned oscillating circuits ; simply a small
induction coil with an independent vibrator, and
the spark gap connected in parallel to an aerial
and ground or counter capacity. This instru-
ment is very largely used by the French Gov-

m -J^**V

Students learning to direct artillery fire by wireless.
Photo Bureau of Public Information

142

TEXTBOOK OF MILITARY AERONAUTICS

ernment for directing artillery fire, where it is
essential that the installations be of light weight,
with a range of communication of from 12 to
15 km.

An independent interrupter is used, and mu-
sical notes are emitted with a frequency of about
300. The secondary of the induction coil has a
verj^ high inductance, so, when connected with
the aerial and ground, it is in tune with the pri-
mary vibrating circuit. Across the secondary
are connected the spark-gap terminals, mounted
on top of a small metal case and on the outside
of the instrument, so that advantage is taken of
the continuous rush of air to cool the gap which
is very small. This gap consists of a copper
tube %" in diameter, Me" thick for one electrode
and a flat disc %" in diameter for the other.
By connecting the aerial and counter capacity
directly across the spark-gap, the necessity of
tuning is eliminated. The aerial wire system
is an open oscillator, and has a capacity of
.0002 mf.

The only essential change recently made was
in tuning the vibrator and connecting the con-
denser across the interrupter and the primary of
the induction coil, as in the Dubilier system ex-
plained later, instead of the condenser across the
interrupter alone, as was customary heretofore.
Under these conditions the efficiency of the in-
strument is considerably increased, and the rea-
son for this will be shown. The battery is in a
small case containing 10 six-ampere hour cells,
the current of which is regulated by a small va-
riable resistance. An ammeter indicates at all

times whether the set is in operation, and how
much power is being used; which is usually 40
watts. With a capacity of .0002, the aerial
wire system radiates 1/9 ampere. The trailing
wire, which is used as the aerial, is about 175 ft.
long, and has a 2 lb. lead weight attached to it.
The engine and all the other metallic parts on
the aeroplane are used as the counter capacity.
This instrument is used mostly for short dis-
tance communications by the rapid, light ma-
chines which are constantly circling over the
trenches, and directing the artillery shots.
Communication is held with the receiving sta-
tions situated about 1 mile behind the guns, and
from there to the gunners a regular telephone
line is used. This instrument is shown in Fig-
ure 1.

The position of the pilot and observer is very
dangerous, as they must be constantly over the
enemies' trenches directing the shots, if they are
long or short, or too far to the right or left. It
is surprising to see how rapidly and automati-
cally the whole system works. As soon as the
shots land, signals are immediately flashed back,
and the next shot follows the corrected course
indicated by the radio apparatus from the aero-
plane. These flying machines must be very
light and rapid, due to the dangerous service
they render. They are usually two-seaters,
containing the pilot and the observer, and so
one will appreciate under these circumstances
how essential a few pounds would be in the wire-
less installation. In constructing the con-
densers for these installations, the Government

The transmissions and
aerials on a French bi-
plane.

RADIO FOR AEROPLANES

148

AE.RI AL

Photograph of Zeppelin showing the aerial hanging down.

informed us that we must eliminate the alumi-
num castings which are used for compresses and
heat radiators, and must cut the containing box
down so that the wall is not more than %". We
thus reduce the weight about 1/4 lbs., which sat-
isfied them very much more than the former
ones constructed from careful experiments.

I have been informed by the commanders that
this aeroplane and radio work has been the most
effective done in the war. It has been by means
of this radio communication that it was possible
for the artillery to break up the strong concrete
trenches. I was in France when the famous
Champagne district siege was begun, and the
returning officers informed me that the Gei-man
trenches were constructed as though they were
foundations for large buildings, heavy concrete
walls reinforced by steel; the only way it was
possible for them to make any advance, was to
completely break up these trenches, and only
by continuous bombardment was it possible
to get the men to move and make any ad-
vance.

The flying machines never stay out for longer
than three hours ; when they return the batteries
are changed.

Another set of instruments used for aero-
plane work, but of a much higher power, is one
using the Bethenod resonance alternator. This
outfit is shown in Figure 2, installed on a

French aeroplane. The special feature of this
apparatus is the large power coupled with the
light weight, which is made possible by the use
of Bethenod's High Frequency Generator.
The principle of this alternator is well known,
and no further details are necessary.

This instrument is made in two different
sizes. One weighing 35 kilos complete, about
77 lbs., has a transmission radius of 110 km.,
about 60 miles. The larger outfit, which weighs
about 110 lbs., has a communicating radius of

I CHOUNO

Methods of suspending aerials from dirigibles.

144

TEXTBOOK OF MILITARY AERONAUTICS

Two French wireless receiving truclis' screened from the eyes of the enemy aviators h\ trees and branches.

about 200 km., about 120 miles. The generator
for 750 watts outfit at 25 volts with a frequency
of 1,500 cycles, is run at a normal speed of 4,500
revolutions per minute. The weight complete
for the generator is 19 kilos, about 42 lbs., and
can be overloaded up to 1 KW. Here is a gen-
erator with % KW outfit, which weighs only 42
lbs., and using a very high frequency makes it
possible to cut down the weight and size of the
other parts of the installation. In the tests
made with this instrument, communication was
held from an aeroplane to a land-station for a
distance of 100 miles, with a complete installa-
tion which did not weigh more than 110 lbs.,
so we have here a basis upon which to work; a
weight of 1 lb. for each mile communication.
The apparatus is constructed with a fairly good
co-efficient of security, in order to support the
shocks of vibration it has to experience. The
sending outfit includes the generator, a trans-
former, an oscillating circuit, and an aerial wire
system. The aerial consists of a bronzed.

braided wire, having a high mechanical strength,
and hanging down and back of the aeroplane.
The diameter of this braid is about 1 mm., and
it is rolled on a very light and insulating wheel,
as can be seen from the figure. The end is an-
chored by a 3 lb. mass which is so shaped that
when the aeroplane is in action, the aerial wire
is nearly in a horizontal position, thus having a
minimum surface exposure. The wheel upon
which this wire is rolled is fitted on a circular
contact, with facilities for quickly rolling and
unrolling the wire while sending, for by that
means the aerial wire-circuit is tuned. In case
of emergency, an insulated clipping is provided
by automatically cutting off the wire. The
counter capacity consists of all the metallic
parts of the aeroplane connected together, which
include the engine, the generator, and other
wires used.

The apparatus, including the wheel, the clip-
ping, and the frame, is so built that it is ad-
justable to any type of flying machine.

Looking inside a wireless receiving truck.
Two officers are receiving messages from aero
observers and transmitting them to the bat-
tery. On<' of them is shown making a record
of the information on his chart of the sector,
which corresponds with the chart used by the
observer.

RADIO FOR AEROPLANES

145

The transformer is of a close core, air-cooled
type, without magnetic leakage, and due to the
very high frequency (1,500 cycles), it is made
very light and small (Figure 2). The oscil-
lating circuit is constructed for a maximum
wave-length of 500 meters, when a condenser of
.012 mf. capacity is used. The inductance con-
sists of a flat helix, with an insulating handle
for continuous variation for changing wave-
lengths. An interesting feature of this instru-
ment is the spark-gap, which is shown at A in
the figure, and consists of a tube and plate. It
is so constructed that the system of ventilation,
that is, the rush of air which is generated by the
aeroplane in motion, is used for quenching the
spark. The tube end of the spark has a funnel,
B, into which the air rushes. The primary
power supplied is 30 amperes at 25 volts, and
the secondary voltage 3,500. A small, light-
weight key is designed for manipulation, and by
means of a rheostat, the musical note of the
spark can be changed from a deep sound to a
whistle. The oscillating circuit, as shown in
Figure 2, contains the hot wire ammeter, the
condenser, the inductance, and the spark-gap
mounted on a separate frame. The sliding con-
tact is shown at E, and is so constructed that,
when revolved, the springs are expanded and it
slides easily over the ribbon, a very desirable
feature in constructing sliding contacts for flat
inductances. In the very beginning, tube con-
densers were supplied, but now the English,
French, and American Governments are speci-
fying Dubilier condensers for aeroplane instal-
lations. The condenser is one of the most im-

— ^/\w — I

Fig. 4.

portant parts of the outfit, for not only must it
be unbreakable, but of small size, light weight
and highly efficient. For that reason I will de-
vote a little time to explaining the construction
of this condenser, which is used now in almost
every aeroplane installation.

In constructing condensers, the space, weight,
and resistance must be kept very low, and
hysterisis loss and brush discharge must be prac-
tically eliminated. Also the condenser must be
able to stand up, and not change its capacity
after usage for a certain time. The British
Government specifications call for a condenser
that should be well built, within 5 per cent, of
the specified capacity, and that capacity should
not change 5 per cent., after strain by a continu-
ous overload, for one hour. Only certain ad-
hesive insulation is permissible, as waxes tend to

Partial view of the receiving apparatus inside
of one of the wireless trucks.

146

TEXTBOOK OF MILITARY AERONAUTICS

The reel and long copper tube of the Culver set through
which the trailing aerial is paid out. This reel has now been
replaced by one carried in the cock-pit.

greatly increase hysterisis loss. As the capacity
is proportional to the dielectric constant, this
should be kept as high as possible for a given
weight and size. It should have a very high
specific resistance, and a low internal resistance,
and be able to withstand twice the voltage. As
the hysterisis loss in the condenser increases as
the square of the voltage, it becomes a serious
problem when capacities for high voltages and
high frequencies are desired. The resistance
must be kept as low as possible, and if the con-
denser is to be enclosed, which it is, all losses
must be kept low, in order to prevent serious
heating. Furthermore, means must be pro-
vided for radiating the little heat which is gen-
erated, and so the condenser is constructed to
be able to stand a certain rise in temperature
without harmful results. Under these condi-
tions only homogeneous dielectrics can be used.
No air or water must be allowed to find its way
near the dielectric substance, since only a small
trace is liable to reduce the strength and effi-
ciency.

The set most used by the Allies on aeroplanes,
and which is probably the most interesting of
the portable installations, is one designed and
built by a Mr. Rouzet. It is shown in Fig-
ure 3. These sets are made for various powers,
but the one most supplied has a capacity of 150
watts, the energy being obtained from an alter-
nator driven by the aeroplane engine. While
various installations for this capacity are being,
made by the Governments, this set deserves
much consideration, especially on account of the
remarkably low weight. The complete trans-
mitter, including the self -exciting generator for
150 watts, weighs only 17 kilos, about 37^/1' lbs.,
which is less than 11- of the weight of the smallest
set made in this country up to 1916. This in-
stallation utilizes a 250-cycle self-exciting al-
ternator, driven by a belt, and is of a remark-
ably light construction, having an armature
with two commutators, one being for D. C,
used for exciting. On the shaft of the arma-
ture is mounted a synchronized spark-gap, from
which a group frequency of 500 is obtained.
The key is connected in the field of the gener-
ator. The transformer is close-cored, oil-
cooled, and is enclosed in a fiber tube as shown
in Fig. 00. The condenser and the tuning coil
are very light but rigid.

In testing the instrument, I found at the end
of 10 minutes the frame became overheated.
However, the cooling effect obtained by the
aeroplane traveling through the air at the rate
of 60 miles an hour is taken advantage of, and
under these circumstances the apparatus works
very well. In my opinion the army and navy
should utilize such an instrument for aeroplane
work.

By means of a standard aeroplane aerial, I
have seen this outfit radiating 1/4 amperes,,
communicating a distance of 50 miles. Tiiis
transmitter was designed with the aim of real-
izing a commercial system in which there will be
no special or peculiar factors. A simple alter-
nator is used, which easily permits the produc-
tion of a high-tension current necessary to
charge the condenser, which, in turn, produces
high frequency oscillations by means of a syn-
chronized gap, a condenser, and inductance.
The resonance of the different factors is very

RADIO FOR AEROPLANES

147

essential, and the following points were consid-
ered in originally designing the apparatus.

First, the condenser is charged in the most
favorable manner.

Second, the condenser is discharged through
a suitable circuit at the most favorable moment,
and.

Third, the injurious results which accompany
the discharge of a condenser, and the operation
of such an instrument, were reduced to a mini-
mum.

This was accomplished by the use of a syn-
chronized spark-gap which is attached to one
end of the shaft of the generator. This gap is
made minutely adjustable, in order that the dis-
charge may take place at the most favorable
moment, the reasons and characteristics of
which are well known. In the design and con-
struction of this gap, the resistance is reduced
to a minimum at the instant of the discharge.
Then an air blast is thrown at the gap after the
first few waves have passed. The dui'ation of
the discharge is reduced to a minimum by point-
ing the spark electrodes.

All the factors in the instrument are care-
fully tuned, such as synchronizing the spark-
gap, which permits of the proper time of dis-
charge and also the time of charge, correspond-
ing to the variations of the alternating feeding
current. This, of course, is the most important
feature of the instrument. The time of dis-
charges are regulated not only by speed, but
also by placing several gaps in series on the
same wheel.

The generator is driven at a speed of about
4,500. In the construction of the apparatus

A French wireless set about to be mounted on an aeroplane.

The set being mounted on the aeroplane.

The set mounted on the Maurice Farman biplane.

The observer operating the wireless.

One of the French machines used for wireless signaling.

148

TEXTBOOK OF MILITARY AERONAUTICS

Powerful wireless apparatus installed on Breguet aeroplane.

aluminum is used wherever possible, even for
the aerial, the length of which is usually about
60 meters. The installations are supplied for
aeroplanes with capacities up to 1 KW, and
consist of the following parts :

The generator, with synchronized gap at the
end of the shaft, a transformer, a condenser,
variable inductances, accessories, such as con-
nectors, hot wire ammeters, antennae parts, in-
cluding the guide.

The total height of a 400-watt set is 12y2
inches, length 175^ inches, the width, including
shaft, 16 inches. It has a remarkably low
weight of 55 lbs., and including the accessories,
70 lbs.

A smaller installation, having a capacity of
80 watts with a height of 9 inches, a length of
12 inches, and width of 10 inches, and a total
weight, with accessories, of 33 lbs., is able to
communicate a distance of 15 to 20 miles.

The 1 KW installation has a height of 21
inches, length, including shaft, 18!^ inches, and
width 15 inches. The weight of this set, com-
plete with accessories, is 182 lbs., remarkably
low for such a big capacity. The length of
waves can be varied up to 600 meters. The dis-
tance of communication for such an instrument

is about 200 miles from dirigibles, and over 100
miles from aeroplanes.

One will note the remarkable characteristics
of such a high-powered instrument, especially
the low weight and volume. Taking these fac-
tors into consideration, radio engineers will see
that this instrument in efficiency, as compared
to weight and distance, is far greater than any-
thing yet installed. In general, the question of
efficiency for aeroplane installations resolves it-
self down to two points, — weight and distance.

What does it matter how mudh power is used
or what does it matter what wave length is gen-
erated, so long as efficient transmission can be
had over the greatest distance for a given
weight? That instrument is the best. If one
could build a 1 KW set which only weighed 25
lbs., but which did not communicate for a
greater distance than the low-powered sets,
there would be no gain or no advantage in mak-
ing a high-powered set of light weight. So
long as the two factors, distance for given
weight, are very efficient, the instrument is effi-
cient; and we hope in the future the lessons
taught will be considered by designers of radio
instruments.

In the early days of the war, when it was
found that aeroplanes had become such an im-
portant factor for defensive and offensive pur-
poses, the commanders and the aeroplanes called
for a reliable instnament which will transmit in-
telligently, but which will have a very light
weight. The outcome of this was the instru-
ment above mentioned.

The current generated by the alternator,
which is self -exciting, is fed to a close-core trans-
former at 120 volts, the secondary of which
charges the condenser at about 12,500 volts.
Troubles usually present in stationarj^ spark-
gajjs are eliminated. Air currents caused by
the rotation and the movement of the aeroplane
greatly assist the detonization of the spark-gap
and cool the electrodes; hence it is possible to
use a large current without danger of arcs form-
ing. In this particular ai)paratus the gap-
length is less than the length which the potential
used can jump across. Since this gap is revolv-
ing at a very high speed, a short-circuiting effect
takes place, for, when the projections of the re-

RADIO FOR AEROPLANES

149

volving electrode approach the stationary elec-
trodes, the discharge takes place, and the dis-
tance becomes shorter, the gap resistance and
the energy consumption being reduced to very
low values. This instrument, therefore, com-
bines the two advantages of comparatively high
initial voltage with a relatively short average
gap-length; when the oscillations of the dis-
charge have become very low in amplitude, the
gap-length is very short. The value of the in-
ductance is veiy important in the operation of
this gap, for it is necessary to carefully regulate
the retardation of the discharge.

The possibilities of radio engineering would
be greatly extended if a small, simple wireless
outfit were marketed, which could be used for
short distances up to 100 miles and utilizing di-
rect current, which is available on almost every
ship, and which is much easier to generate.

With this object in mind, the following appa-
ratus was designed. The idea occurred to me,
in experimenting with condensers across the in-
terrupter of the ordinary induction coil, that if
the oscillations set up in this condenser were

passed through an inductance, and the time
period made the same as the vibrator, the effi-
ciency of the ordinary induction coil would be
greatly increased, for, although this instrument
has been in use for a good many years, it is well
known that the ordinary induction coil is very
inefficient. It was to utilize the current wasted
in the condenser that I conducted a series of ex-
periments in 1909, which led up to the following
system.

I found that by means of tuning the oscillat-
ing circuit across an interrupter, or any kind of
a condenser-charging device, that sparking and
arcing are almost entirely eliminated, and that
musical notes can be obtained, especially on the
smaller type instrument, up to a very high pitch.
Due to this tuning of the oscillating circuit, the
efficiency, considering the power input to the
power of the aerial, is greatly increased, for in
the very beginning we eliminate the great loss
which is common with a small motor-generator
set for producing musical notes. In order to
obtain the properties and characteristics of the
musical note from direct current by an ideal im-

An aeroplane being used for artilkry lire. The aciuplanc tiicle, u,er tiie iuiag batteries and the obsci

the shots and directs the man behind the guns by wireless.

liic effect of

150

TEXTBOOK OF MILITARY AERONAUTICS

Lightweight wireless vibrator
aeroplanes.

for

Compact form
unit.

pulse excitation, the connec-
tions are made as shown in
Figure 4. G is the direct- pj y
current source which passes
through an inductance, A,
an oscillator or condenser charging device, B,
another inductance, L, which acts as the pri-
mar)'^ of the transformer, and a condenser, C.
In the small-tj'pe apparatus the inductance. A,
acts as an electro magnet for operating the oscil-
lator, B. We now have an oscillating circuit,
BCL. C is made variable so that it can be
tuned to a desired frequency, which, supposing,
for example, is 500 per second. The condenser
charging device, B, has a working frequenc}^ of
its own, and the two elements, that is, the oscil-
lator and the oscillating circuit, are brought into
resonance. Then, and only then, a steady and
even current is produced in the secondary of the
transformer, which charges a high-tension con-
denser. On types of apparatus using up to 500
watts, a magnetic mechanical oscillator can be
used, and in this case the electrical frequency of
the oscillating circuit, BLC, will control to a
certain extent the mechanical frequency of the
oscillator. That is to say, it will force the oscil-
lator to charge and discharge a condenser at a
desired frequency, so as to keep in step with the
current. The reasons for this will be explained
later.

Mechanical interrupters and condenser-
charging devices can be considered as variable
resistances. In the operation of an ordinary in-
duction coil, care mus-t be taken to obtain in the
interrupter the greatest possible variation of
potential. This is generally prevented by the
currents at the so-called opening spark. Heat-
ing troubles are experienced at the contacts and

Fig.

Wireless aero transmitter.

of wireless

50 volts. This
the contact is

arcing occurs. When the
contacts of an induction coil
are opened, a small arc is
formed, and if the current is
over 2 amperes, we have a
potential difference of about
remains continuous, even if
opened by a millimeter or
two. With weaker currents the arc potential
is higher, so that with the small working po-
tentials onlj^ small opening sparks occur. To
remove this arc and to obtain higher poten-
tials at the interrupter, condensers are con-
nected in parallel. When the contacts are
opened, the arc rarely exists below 50 volts, but
in the meantime, however, the point of contacts
have already been extended, and the potential
difference rose to several hundred volts. If,
however, inductance is added, we will have cur-
rents stored up in the condenser which will dis-
charge in a certain time, depending upon the
values of the inductances and the capacity.

I therefore tried to obtain a condenser-charg-
ing interrujiter which would operate when prac-
tically no current was passing, to prevent any
potential difference occurring immediately after
the interrupter was opened and closed; either
case of which would cause the current to jump
across the small air-gap. This condition can be
fulfilled bv means of the resonance oscillator and

RADIO FOR AEROPLANES

151

circuit. Figure 5 shows a curve of the different
currents, and the action taking place in the oper-
ation of the apparatus.

OY represents the currents and OX the time.
For the purpose of illustration, suppose the
origin to commence on the moment when the
condenser of the tuned oscillating circuit is fully
charged, and the oscillator is closed. If this
oscillating circuit were kept closed permanently,
the condenser would discharge through the oscil-
lator, and the primary of the transformer as a
damped wave, indicated by the curve OABCD.
At the same time the primary current gradually
rises from zero, according to the ordinary ex-
ponential law, as shown by the curve OVEFG.
In this type of apparatus the inductance, A, acts
upon the oscillator, so that OY' represents the
current through the magnets necessary to pro-
duce a force equal to the controlling force of the
spring.

In all types using an electro-magnetic-con-
trolled oscillator, A is the magnet coil operating
on a spring which controls the oscillator, D.
Let O Y' represent the current through the mag-
nets necessary to produce a force equal to the
controlling force of the spring. This is also
shown at E. The magnetic force of the coil, A,
however, must be a little more than the force of
the spring, in order to control it. This is shown
at F. When the primary current through the
magnet coil. A, reaches this point, F, the oscil-
lator is opened.

For there to be no sparking or arcing at the
oscillator, there must be no current flowing when
it opens. Adding, therefore, the two cui-rents,

An improvised receiving station constructed with aeroplane
packing boxes.

going through the oscillator and the primary of
the transformer, represented by the curves
OABCD and OVEFG, we get OHKEN, the
curve of the total current. This curve, it is
seen, falls at zero when the ordinate NC is equal
to the ordinate NF. It is therefore evident
that, by varying the capacity E and the resist-
ance or inductance of the primary current sup-
ply, which determine the curves OVEFG and
OABCD respectively, it becomes possible to so
adjust the factors that OHKN reaches zero at
the instance of rupture of the circuit, and under
these conditions there will be no sparking at the
oscillator.

The primaiy current through the coil A does
not cease instantly, but slowly dies away as the
condenser, C, charges, such as is shown by curve
FP. This is the charging current for the con-
denser. We complete the corresponding curve,
CQR.

This charging current flows through the coil
A and serves to retain the oscillator, thus keep-

A "T. S. F." (telegraphic sans fils) post which
receives the messages from the aero observers
and transmits them to the gunners on the French
front.

152

TEXTBOOK OF MILITARY AERONAUTICS

Permanent German wireless stations, used by Zeppelins be-
fore the war. It is understood that the number of these sta-
tions has been increased greatly since the war.

ing the oscillator open until some such point as
S is reached, the ordinates OS being slightly less
than OY. Here the oscillator closes again and
the operation is repeated, commencing from the
point D.

From the above it is obvious that the induc-
tance, A, resistance, R, and capacity, C, play im-
portant parts for the smooth operation of this
instrument, and this is very well proven by ex-
periment. Further in order for the note to be
a pure one, it is necessary that the second cycle
must commence precisely at the point D, and
this can be secured by varying resistance R and
the tension of the oscillator reed.

Furthermore, it is at once seen that if the ca-

Wirelru receiving apparatus.

pacity, C, is increased, the curve FSP Avill de-
crease less rapidly, and consequently the effec-
tive duration of the current through C, repre-
sented by distance ND, will be increased, and
therefore the contact will remain open for a
longer period, closing at some such point as T.
But the curve OABCD will also have a greater
time period, and will therefore approach zero at
some point near T, so that the effective fre-
quency of the oscillator is lowered. Resonance
is then obtained by re-adjusting the primary re-
sistance R, or spring, on the oscillator.

If the voltage is lowered, the new curve of rise
of the current will not reach so high an ampli-
tude; hence the time it is above the line Y EZ
would be shortened and the frequency increased,
but resonance is again obtained by increasing
the capacity.

The same result can be obtained by revolving
commutators, but in this case the time of contact
and the time that the circuit is open must be
regulated with the primary curve and the con-
denser capacity. Then practically the same re-
sults and curves can be applied.

Going back to Figure 4, by substituting an
oscillator at B, which has a continuous varying
resistance, such as a microphone-carbon cup, it
can be seen at once that sine waves could be
generated at S, whose frequency will be equal
to the frequency of the oscillating circuit CLB.
The frequency, however, is limited by mechani-
cal action, but for laboratory use, I have con-
structed a small oscillator whose movements are
very small, but sufficient to produce alternating
frequencies almost beyond audibility. In using
revolving commutators, the amount of fre-
quency that can be obtained depends upon the
speed and the size of the contacts, so that in
order to obtain radio frequencies with such an
apparatus, almost cannon-ball speed would be
necessary, which is mechanically impracticable,
although the contacts can be very small for large
powers, and may be divided into any number,
making and breaking at the same time. If it
weie possible to make and break the circuit, at
a radio fre(iuency, under this system an ideal
wireless outfit could be produced, with efficien-
cies unknown heretofore.

Figure 6 illustrates a little instrument used on

RADIO FOR AEROPLANES

158

During the Balkan War aeroplanes were first used to spot artillery fire.

?-^4^^'-V ;^t

aeroplanes with direct-current storage-batteries,
30 volts.

An Allied Government has ordered a num-
ber of these sets for aeroplane work which
utilize a small direct-cur-
rent generator. This is
the simplest form of gen-
erator suitable for aero-
plane use, as it takes up
smaller space and is of
lighter weight for a given
power than any other
sources supplied. The
instrument used is shown
in Figure 7 and operates
on the Dubilier principle
of producing musical al-
ternating currents from t
direct, without the use of
a motor generator set.
The complete weight of
the apparatus is 32 lbs.
for 150 watts, which is
sufficient to communicate

a distance of over 50 miles. In Figure 7, the
operation of this instrument is the same as
shown in the diagrams. The quenched spark
gap. A, is one especially designed for aeroplane

The Cutting A Washington aerophone radio set.

154

TEXTBOOK OF MILITARY AERONAUTICS

instruments, for it combines a large sparkling
and cooling surface with light weight and small
space, and consists of a long, flat, copper, cast-
ing-bar separated about .005", between which
the sparking takes place. A is a hot-wire meter
which will indicate at all times the amount of
current which is being radiated, and D is the
primary current which shows how much power
is being consumed.

Experiments were tried both in France and
in this country in using an aerofan to drive the
generator for the source of supply to operate
the wireless instrument.

A patent recently issued to F. W. Cotterman
comprises a generator for use in aeroplane work,
wherein constant potential is obtained irrespec-
tive of the speed of the generator by means of
gears.

Figures 9 and 10 show installations used by
the German Government.

Figure 11 shows the method of suspension
from the Zeppehn. Great care must be taken
here that sparks and induce currents do not ig-
nite, because at first it was thought utterly im-
possible to install wireless apparatus on balloons,
on account of this danger. Figure 11 shows the
method of suspension wherein the instrument is
entirely isolated from the bags.

In connection with aeroplane work it is nec-
essary that automobile stations be equipped so
that they can communicate with these aeroplanes

The fan-<lriveii ({'■'""''''toN '<"■ """ Culver sot, which fiiriiishc-<i
power to lend message* over a distance of 140 miles.

from the field, and if necessary be quickly mov-
able. Figure 12 shows an interior of an auto-
mobile equipped with a 2 KW transmitter,
which can communicate up to a distance of 150
miles or so.

Germany has long foreseen the possibilities of
wireless communication in connection with aero-
nautics and for that purpose has established a
chain of stations around Germany which are in
constant touch with aeroplanes and balloons, the
same plan we are now trying to carry out in this
country. It may be interesting to note that this
is veiy old and has been utilized in Germany
years ago. Figure 14 shows the location of all
the wireless stations around Germany, espe-
cially used for aeroplane and Zeppelin com-
munications.

iVIany experiments have been made to find out
the best possible method of mounting aerials for
radiating along surfaces. The most convenient
and general all-around efficient means is to drop
a trailer, and to use the rest of the metal parts
of the aeroplane as the counter capacity. Fig-
ure 15 shows a wireless aerial on a Flanders
aeroplane, and it may be interesting to note that
this picture was taken two hours before both the
pilot and the operator were killed by the same
machine falling.

Figure 16 shows a German Taube. Here
can be seen plainly how the aerial is mounted
on two small masts on the extreme of the wings.

Figure 17 shows other methods of suspending
aerials, and methods of transmitting electro-
magnetic waves from air-vessels.

For aeroplanes it is practically impossible to
receive signals, and never necessary. It is only
important to send, and very rarely does an occa-
sion occur where the operator or pilot has need
or time to receive messages. However, many
attempts were made to produce instruments
which would make it practical to receive on aero-
planes, but up-to-date no such instrument has
yet been perfected. On account of the noise
due to the engine and the wind, it naturally be-
comes very difficult to distinguish signals by
means of the ear. Figure 18 shows an airman's
helmet, where the receivers were constructed
right inside the head-gear, with cushions all
around to eliminate the noises, but then the vi-

RADIO FOR AEROPLANES

155

brations of the body and slight unavoidable
noises transmitted directly through the body
make it impracticable to receive in this manner.
However, it is not impossible to make an instru-
ment wherein the received signals can be distin-
guished by means of variation in light, for vibra-
tion and noises will not interfere with one's
sight. Experiments have been conducted along
these lines, receiving the wireless signals by an
illuminating method, and Figure 19 shows an
instrument constructed on the principle of an
eithoven galvanometer, wherein the operator
looks into the two eye-pieces and can see the
movement of lights, indicating dots and dashes.
This instrument, however, is not perfected as
yet so as to be called practicable.

Due to encouragement given radio engineers
by the radio division of the United States Navy,
an apparatus has recently been developed in this
country which is far superior to any used in
Europe. Of the different installations recently

purchased by the Navy, three different princi-
ples were utilized for the protection of electric
oscillations.

The apparatus supplied by the Marconi Co.
and E. J. Simon of New York, uses a 500-
cycle generator, the former with 1 KW capac-
ity, sufficient to communicate about 300 miles,
weighing complete, with generator, 100 lbs.,
while the latter with about 750 watt capacity,
250 miles distance, weighs complete 100 lbs.

Apparatus, using a glass bulb-generator, has
been supplied and built by the De Forest Tele-
graph and Telephone Co. and Western Electric
Co.

Apparatus using direct current, designed and
patented by William Dubilier, is being supplied
by the Sperry Gyroscope Company. It utilizes
the quenched-arc principle and a complete in-
stallation, weighing about 65 lbs., with the gen-
erator of 500 watt capacity can radiate over 6
amps., and communicate about 250 miles.

A Zeppelin over Berlin. In the foreground is the Hindenberg statue.

An American "Blimp" and obscrvaliein balloon nt the Goo<lyear School, Akron, Ohla

Passed by the Censor.
ISO

CHAPTER XII
MILITARY AEROSTATICS

Military aerostatics comprise three branches,
as follows:

(1) Dirigibles, which are used extensively
for night scouting, bombing, and, to some ex-
tent, for transportation of military personnel
and material to otherwise inaccessible places;

(2) Captive Observation Balloons, which
are used for directing artillery fire, and for gen-
eral observation;

(3) Spherical Balloons, which are now used

scription of the latest Super Zeppelins, see
chapter on Naval Airships, "Textbook of Naval
Aeronautics," Century Co. publishers.

(2) The semi-rigid dirigible has a rigid
longitudinal frame usually immediately below
the gas bag; this frame serves to distribute
evenly the ascensional strains against the sup-
ported weights of engine, passengers, etc., to
prevent buckling of the gas bag which in most
dirigibles of this class depends upon internal gas

only for training captive balloon and dirigible pressure to maintain the shape of the envelope.

pilots.

Dirigible Balloons

Hundreds of dirigible balloons, ranging in
size from the small "Blimp," about 180 feet
long, to the huge 700 foot "Zeppelin," are used
in the present war. The "Blimps" are used
mainly for coast patrol and convoying ships, by
day and by night; and the large Zeppelins are
used in night bombing attacks and in naval op-
erations.

In France, Russia, Italy, Germany, and Aus-
tria, there are military dirigibles, differing in
form from the naval dirigibles. In Great
Britain all the dirigibles are in the navy.

The United States was one of the first coun-
tries to build a dirigible for military purposes.
Bids were invited in 1907-08 for a dirigible for
the army.

Rigid, Semi-Rigid, and Non-Rigid Dirigibles

Three types of dirigibles have been used by
the European countries: (1) the rigid; (2) the
semi-rigid; (3) the non-rigid.

(1) The rigid type of dirigible is one in
which the shape of the gas compartments is
maintained by means of rigid framework, such
as the Zeppelins and Shiitte Lanz. For de-

ls:

The French dirigibles of the Lebaudy class are
examples of the semi-rigid type.

(3) The non-rigid dirigibles depend en-
tirely on gas pressure within the envelope to
maintain shape; the nacelle being suspended by
net of longitudinal canvas bands sewed to the
envelope. Dirigibles having a long rigid
framework nacelle suspended some distance be-
low the envelope are usually included in the non-
rigid class. The Beachy airship and armj^ Di-
rigible No. 1 (1908) of several years ago are
the best known non-rigid types in this coun-
try.

Military Observation Balloons

When a few years ago the aeroplane proved
to be successful, and the attention of practically
all students of aeronautics was drawn to its
development for military purposes, interest in
the captive balloon as a means of observation
waned, not only in the United States, but
abroad. In our case, the lack of sufficient ap-
propriations for the aeronautical service of the
army was also largely responsible for our
failure to develop this valuable auxiliary.

The present war in Europe has demonstrated
that the aeroplane, while of the greatest value
for aerial reconnaissance, is not able to replace
the captive balloon for certain purposes. So
thousands of kite balloons are used in the pres-

ve^rnc/ti. Sei^Ais Srifces/teo

/^yfA/ei/y^/? y,v^ if^

■/fi/'/'//i/ff ^/r/i/et.

Sif/£>jr Ji, /7/vc zzo/f /fa fie /"aaai £

~Azzcnaff & /fofir

-ff/fSArr

TTie Spherical lialloon — used mainly to train pilots for military observation balloons. The balloons range in size from

30,000 to 80,000 cubic feet.

MILITARY AEROSTATICS

150

ent war for directing artillery fire and observa-
tion.

The great advantage of the captive balloon is
that the observer is constantly in direct tele-
phonic communication with the artillery com-
manders in his vicinity; constant and thor-
ough inspection of the enemy's positions with
the aid of powerful glasses and telescopes
reveals every movement of bodies of troops
or anything new that has appeared during
the previous niglit, and the targets thus pre-
sented can be immediately taken under fire.
Continuous and searching observation of the
same sector enables an observer to note even
slight changes in the color of the earth and
to make important deductions therefrom.
Changes in trench construction can thus be
easily detected.

One observer on the western battle front in
France states that he was able to count twenty-
six balloons in sight at one time ; this is convinc-
ing testimony of their extensive use. It is an
interesting development of the present war that
battle type aeroplanes ai'e assigned for the pro-
tection of the captive balloons and for this pur-
pose cruise about at a height of several thousand
feet above the balloon, ready to swoop down
upon any enemy aeroplanes that attempt to
destroy it.

Frequently, anti-aircraft guns are located
sufficiently near balloons to maintain barage
fire over them to prevent hostile aeroplanes
from approaching within range of their in-
cendiary rockets or bullets.

The spherical type of captive balloon has been

abandoned in favor of the elongated type, often
referred to as "sausage" or "drachen" (German
for kite) balloon, since the latter type has
much greater steadiness in the winds; the pres-
sure of the moving air against the under side of
the balloon holds it steady in the same manner
as in the case of the common paper kite.

The kite balloon is fitted with a tail consisting
of several conical canvas cups, to assist in main-
taining its stability, with the same result as is
secured by affixing a tail to the toy kite. The
latest type of captive balloons are made with
stream line shape and fins so that the kite tail-
cups are not required for steadiness, and conse-
quently should not properly be referred to as
kites.

Employed at Night as Well as in the Daytime

In Europe the observation balloons are
placed from two to four miles in rear of the line
of trenches, and are separated by intervals de-
pending upon the artillery activity in various
sectors. The altitude at which they are held
is dependent upon the atmospheric condi-
tions and upon the distance of the enemy's
artillery. They are usually sent up at daylight,
and remain in the air until dark, being drawn
down every few hours to change observers.
Occasionally they remain up at night, and it is
frequently found that enemy guns that are not
visible by daylight may be located at night by
their flashes. Even after dark it has been
found that observers who have studied every
feature of the ground for days are able to see

The winch for the kite-balloon mounted on a ^7?
truck.

160

TEXTBOOK OF MILITARY AERONAUTICS

One of the new Cacquou type observation balloons used exten-
sively by the Allies.

enough to fix accurately the position of the
flashes. The strain of constant observation
with high-power glasses, or telescopes makes it
advisable to change the observers at frequent in-
tervals.

It is customary to have two officers in the car
of the balloon, and they are connected with the
ground by telephone. One method is to have
an insulated telephone wire in the center of the
cable which holds the balloon; another method
is to drop a strong, light-weight wire from the
basket of the balloon to connect with the tele-
phone circuits directly underneath. In both
cases the steel wires of the holding cable serve
to complete the electric circuit for the tele-
phones.

Balloon companies are provided with tele-
phone switchboards so that the observer in the
basket can communicate directly with any bat-

tery or higher artillery commander in his vi-
cinity.

Buildings, hills, or specially constructed
towers concealed by the trees are frequently
utilized in conjunction with captive balloons to
provide an auxiliary observing station, so that
the two may serve as the end stations of a base
line for the accurate location of targets. In
some cases another balloon is used as the second
observing station.

For Directing Artillery Fire

It has been learned that at the beginning of
the war various special codes of signals were
experimented with for the purpose of enabling
observers to report the error in the fall of shots,
but these have been discontinued in favor of the
brief annoimcement of "over," "short," "right,"
and "left." Field glasses having a milled scale
permit of the observer reporting in degrees the
distance of shots from the target.

For service with the mobile army it was cus-
tomary in Europe before the war to have highly
trained balloon companies, able to inflate a bal-
loon and have it, with its observers, several
thousand feet in the air in about twenty min-
utes after the organization had halted; this
speed was attained by using compressed hy-
drogen carried in special vehicles.

Hydrogen Supply and the "Nurse"

The information of three or more years ago
indicated that the peace strength of the balloon
companies in Europe averaged about sixty men.
The arduous and continuous service that has
been required during the war has necessitated
an increase in the number, there being at the
present time in some cases 160 officers and men
assigned to one balloon; this number pro-
vides for three reliefs for the captive balloon,
the observation tower personnel, the telephone
switchboard operators, and details for the
manufactiH-e of hydrogen.

Since the service along the western battle
front has been in the nature of siege warfare, it
has been practicable to supply hydrogen from
portable field generators, instead of furnishing
it compressed in cylinders.

TEXTBOOK OF MILITARY AERONAUTICS

161

The average capacity of the balloon is
32,000 cubic feet. There is continuous loss of
hydrogen due to leakage through the fabric and
to losses from expansion at high altitudes ; these
losses are ordinarily replaced at night. A com-
mon method of replacing gas is to fill small bal-
loons called "nurses" at the nearest field gen-
erating plant; a small detachment of men can
easily conduct this supply balloon to the hangar
and transfer hydrogen from the "nurse" to the
captive balloon as it may be required.

The Windlass

The most modern tj^pe of windlass for hold-
ing captive balloons consists of a winding drum
constructed on a motor truck.

Whenever enemy aircraft attempt to destroy
a captive balloon, it is customary to haul it
down rapidly or to keep it moving around the
field, to lessen the chances of its being hit. The
moving is often done by using twenty-five or
more men, each having a rope attached to a
snatch block, through which the cable is passed.
These men then walk to various points in the
field, and their movement changes the position
of the balloon not only horizontally but verti-
cally as well.

Captive balloons are occasionally destroyed
by incendiary bullets, arrows, or bombs dropped
by aviators. Destruction in this maimer is not

necessarily fatal to the observers, as they are
usually provided with parachutes attached to
body harness, which permit their safe descent to
the ground.

About eight years ago, while Fort Omaha
was garrisoned by signal corps troops only, a
large balloon hangar was constructed at that
point, together with a plant for generating hy-
drogen by the electrolysis of water and the ma-
chinery for compressing the gas. After its
completion, the equipment was used for about
two years for free and captive balloon instruc-
tion, but its employment for this purpose was
later discontinued for the reasons previously
stated.

The U. S. Army Balloon School is now estab-
lished at Fort Omaha. Commissioned and en-
listed personnel are assembled there, organ-
ized into companies and squadrons, provided
with equipment and given considerable train-
ing before being sent out to serve the artillery
and divisions.

Free Balloon Training Necessary

In case the cable holding a captive balloon
should break, it then becomes necessary for the
observer to descend and land in the same man-
ner as in manoeuvering the ordinary free balloon,
for which reason an essential part of the prelim-
inary training of students at the Balloon School

One of the American Blimps manufactured by the Goodrich Company. (Passed by the Censor.)

III

^»MJL^ ^

162

MILITARY AEROSTATICS

168

consists in the navigation of free balloons and
qualifying as pilots thereof.

The Free Balloons

ITS CONSTRUCTION, INFLATION, AND OPERATION

The present war has brought out the value of
free balloon training, and the sportsmen who
took up ballooning as a sport in the past twelve
years are now as valuable to the cause of na-
tional preparedness as if they had had military
training for that same length of time.

A free balloon is the simplest of all aircraft.
It is essentially a spherical bag made of silk, or
cotton varnished or rubberized to prevent too
rapid diffusion of the contained gas. Coal gas
of light density (4) and hydrogen are the gases
ordinarily used for the inflation of spherical bal-
loons. A net is spread over the spherical gas
envelope and by means of a loading ring the
basket for passengers is attached to the lower
terminal ropes of the net.

In the top of the envelope is a manceuvering
valve the opening of which permits the escape
of gas and consequent descent of the balloon.
The valve cord, usually white in color, hangs
vertically passing down through the appendix
opening within reach of the pilot. When a free
balloon lands in a wind it is necessary to deflate
it veiy quickly in order to avoid being dragged
along the ground ; to provide for this a special
ripping panel is made into the upper surface of
the envelope, so arranged that when the pilot
pulls the cord (colored red) attached to the up-
per end of this panel the stitching rips, thereby
opening several feet of the gas bag and empty-
ing all gas in a few seconds.

A free balloon usually is provided with a long
guide rope and anchor (with separate rope).
The navigating instruments consist of a record-
ing barometer (baragraph) calibrated for alti-
tude measurements, a statoscope, which is also
a sensitive barometer and will indicate changes
in altitude of only six or seven feet.

Synopsis of the Course of Training at United
States Army Balloon School

The course of technical training is both prac-
tical and theoretical, so arranged that the prac-

One ot till- first kite-balloons used by the Aerostatic Section,
U. S. Army at Omatia. (Photo passed by the censor.)

tical instruction will have preference at all times
when weather conditions are suitable. When-
ever high winds or rain interfere with the out-
door training the class room instruction is
held and consists principally of conferences.
The instructor covers the subject thoroughly
and students are expected to ask questions and
join freely in discussion. Practical instruction
in the measurement of density of gases,
testing and adjustment of instruments and sim-
ilar laboratoiy indoor work is conducted
when weather conditions outside are unfavor-
able.

PRACTICAL INSTRUCTION

Generation and compression of hydrogen.

Hydraulic testing of gas cylinders.

Spreading envelopes and assembling parts of
free and captive balloons.

Inflation of balloons.

Balancing free balloons.

Use of ballast and balloon instruments while
on voyages.

Selection of landing spots and drag-roping.

Deflation by valve and rip panel.

Folding, packing, and shipment of bal-
loons.

164

TEXTBOOK OF MILITARY AERONAUTICS

One of hundreds of Kite Balloons, which serve
as the eyes of the artillery on all the fronts, be-
ing towed by its mooring-rope to its anchorage.
There is a Kite Balloon for every heavy gun.
An account of how Kite Balloons are operated
for artillery was given in "Flying" for Decem-
ber.

Replacing of rip panel, repairs and inspec-
tion of envelope and net.

Qualification as balloon pilot according to
F. A. I. rules.

Testing of cordage and fabric for breaking
strength.

Testing of fabric for permeability to gases.

Practical handling of captive balloon wind-
lass.

Filling kite balloons rapidly from cylinders
of compressed hydrogen.

Motor truck operation and maintenance.

Determining course and position of free bal-
loon by use of maps and compass.

conferences: obganization, equipment and
training of balloon companies

Assignment of duties, commissioned and en-
listed personnel.

Transportation and special technical vehicles.

Replacing gas lost by diffusion and expan-
sion.

Replacement of empty hydrogen cylinders.

Field hydrogen generators.

Field compressing outfits.

Meth(Mls of observing and indicating targets
and plotting shots.

Telephone sen-ice from balloons, instniments
and circuits.

Photography and sketching from balloons.
Visual signal codes from balloons.
Property damage caused by descent in free
balloons.

conferences: balloon construction

Kinds of fabric suitable for balloons.

Preparation and application of varnishes for
cotton balloons.

Cordage for nets and suspensions.

Shapes of balloon envelopes and standard
sizes.

Strip and panel construction for envelopes.

Laying out patterns for envelopes.

Various types of seams.

Designs and tests of suspension patches.

Manufacture of nets.

Tj'pes and sizes of manoeuvering valves and
pressure valves.

Size, location, cord attachment and replace-
ment of rip panel.

Appendix ring, neck and cord.

Kite balloon steering bags and substitutes.

Number, size and shape of tail cups.

Strength, weight, flexibility and construction
of cable for captive balloons.

Sizes, types, weight and attacliment of bal-
loon cars.

Essential features of concentrating rings.

MILITARY AEROSTATICS

165

conferences: gases

Kinds of gas suitable for free, captive and
dirigible balloons.

Specific gravity of gases and methods of de-
termining.

Manufacture of coal-gas and water-gas.

Production of hydrogen by electrolysis of
water.

Hydrogen by steam and iron method.

Hydrogen by compression and refrigeration
method.

Hydrogen by decarburation of oils.

Hydrogen by silicon-soda process.

Hj'drogen from hydrogenite and hydrolythe.

Testing hydrogen for purity.

Compression of gases.

Flow of gases through pipes and orifices.

Types of gas-holders and their maintenance.

conferences : meteorology

Indicating and recording, barometers, ther-
mometers, hygrometers and anemometers.

Tests, maintenance and method of mounting
instruments.

Various changes in atmosphere with increas-
ing altitude.

Movement of high and low pressure areas;
direction and rate at various seasons.

Movement of atmosphere over large areas.

Local effect of vertical currents.

Cloud formations and deductions from
them.

Weather maps, weather predictions; storm
warnings and weather signal codes.

Tornadoes and cyclones; seasons and locali-
ties.

Average wind velocity in sections of the
United States.

conferences: dirigible balloons

General types of rigid, semi-rigid and non-
rigid balloons, and employment of each type.

Rigid dirigibles : Dimensions, shapes and ma-
terials used.

Semi-rigid: Dimensions, shape, materials,
important structural features and methods of
car suspension.

Non-rigid: Dimensions and shapes; main-

Drawing reproduced fruiii the "lllublraled Lumlun News," showing the extent of the employment of observation balloons on the

Somme front.

166

TEXTBOOK OF MILITARY AERONAUTICS

taining shape; material for envelopes; methods
of ear suspension.

Air resistance to various shapes and skin re-
sistance.

Size and arrangement of ballonets.

EmplojTnent of ballast.

Vertical and horizontal stabilizing fins.

Rudders for altitude and direction.

Xumber and arrangement propellers.

Gasoline engines suitable for dirigibles.

Number and distribution and sizes of motors.

Gas engine principles and maintenance.

Dj'namic reaction of atmosphere on under
surface.

Velocity with respect to wind direction and
earth.

Na\ igating instruments.

Hangars and methods of entry and exit in
wind.

Designs for descending on water or land.

Bomb dropping devices.

Armament.

Memoranda:

This pliotogrui)h, passed by Uic censor,

shows one of the hangars and some of the balloons at liie L. cj. Army Balloon School at
Omaha, Nebraska. (International Photo.)

CHAPTER XIII

HYDROGEN FOR MILITARY PURPOSES

Notes Prepaked by Lieut.-Colonel C. DeF. Chandler, Signal Corps, U. S. A., for Army

Balloon School

The production of hydrogen for commercial
purposes has naturally been toward the develop-
ment of methods which insure low cost, and the
equipment designed is usually for permanent
installations. Greatest efficiency in the pro-
duction of hydrogen for the military service in-
volves processes which permit of easily trans-
portable generating equipment, ample avail-
able supplies of chemical substances, and purity
of gas. It is often practicable for the army to
use hydrogen plants of commercial types, ship-
ping the gas compressed in cylinders, so that it
is important that officers assigned to the lighter-
than-air service become familiar with all prac-
ticable methods.

Properties of Hydrogen

Hydrogen is a colorless and odorless gas,
when pure. Frequently in the manufacture of
hydrogen by chemical processes impurities in

materials cause combinations of sulphur, carbon
and arsenic, which with hydrogen even in mi-
nute quantities, produces an odor often incor-
rectly referred to as that of hydrogen.

Hydrogen is the lightest known gas, having
a density of .0696, referred to air at the same
pressure and tempei'ature ; this is equivalent to
a weight of .005621 pounds per cubic foot at
temperature of zero degrees C, and 76 cm.
(.001476 grams per cubic centimeter, at zero de-
grees C. 76 cm.). 1 Gram (15.43 grains) at
0° C. 76 cm. equals 11.11 liters equivalent to
678 cubic inches of hydrogen. One grain of
hydrogen at 60° F. and 30 inches barometric
pressure equals 46.45 cubic inches.

Compared to other gases, hydrogen is ab-
sorbed very slightly in water. At 0° C, the ab-
sorption in water is .00192 and at 80 degrees C,
the absorption is .00079 referring to weight
in grams H2 absorbed in 1000 grams of water.
Hydrogen becomes liquid at a temperature of

167

168

TEXTBOOK OF MILITARY AERONAUTICS

A British airship about to ascend.

minus 220 degrees C. when subjected to a pres-
sure of 20 atmospheres. No matter how low
the temperature, the pressure must be at least
14 atmospheres, and, at this critical pressure,
hydrogen liquefies at minus 240.8 C.

The coefficient of expansion of hydrogen due
to temperature changes is .00366 per degree
Centigrade at a pressure of 100 centimeters of
mercury, and between the temperature of 1° and
100° Centigrade. This coefficient of expansion
should be particularly noted for the reason that
in less than 24 hours changes in temperature of
72° F. (40° C.) in the north temperate zone are
not unusual. A lowering of the temperature
40° C. reduces the volume of gas nearly 15 per
cent, causing a balloon of 25,000 cubic feet
capacity to become flabby and have the appear-
ance of losing 3200 cubic feet of gas.

Boyle's Law states that for a constant tem-
perature the volume of gas diminishes in direct
proportion to the pressure, but this applies only
to ideal gases, of which there are none. The di-
vergence of actual gases from Boyle's Law does
not follow any formula ; a curve plotted for any
one gas is irregular at various pressures. ( See

Smithsonian Physical Tables.) Hydrogen is
less compressible than indicated by Boyle's Law,
while nearly all other gases are more compress-
ible. At normal temperatures and a pressure
of 2000 pounds per sq. inch (136 atmospheres),
the quantity of free hydrogen in commercial
cylinders of 2640 cubic inches, should be, accord-
ing to Boyle's Law, 208 cu. ft. whereas experi-
ments show only 191 cu. ft. (Bureau of Stand-
ards.)

Hydrogen will burn in air when the percent-
age is as low as 4i/4, the flame traveling upward
when ignited below. As the percentage of H2
increases to 9, the flame will travel downward
or in any direction. Further increases in per-
centage H2 increase the intensity of the flame
propagation, which when very rapid and violent
is called an explosion. The flame propagation
is increased when the hydrogen is mixed with
oxygen not diluted with nitrogen as in air. Ex-
amples of this power and effect are occasionally
observed when hydrogen and oxygen are acci-
dentally compressed in the same cylinder.

Vitriol Process

One of the oldest and best known methods for
hydrogen production is the vitriol process.
The action of sulphuric acid on iron, or zinc
evolves hydrogen as shown by the following
chemical equation:

Fe + H2SO4 Aq = FeS04 + 2H

It is essential that dilute acid be used for the
reason that concentrated sulphuric acid forms a
film of sulphate of iron on the surface, which
is soluble in water but not dissolved by the con-
centrated acid. This process is so well kno^^^l
that a detailed description here seems unneces-
sary. The generating equipment can often be
improvised by using substantial barrels or vats
of wood or large glass or earthenware carboys,
and lead pipes for conducting tlie acid. The
caution to always pour the acid into the water
and never the water into concentrated acid can
not be repeated too often. Furthermore, when
using improvised equipment or even specially
constructed generators that are not positively
gas tight, never strike a match or carry an open
light such as a lantern near the generators.

HYDROGEN FOR MILITARY PURPOSES

169

It is found in practice that the washing and
purifying of the gas by the usual methods does
not entirely remove the water vapor carrying
traces of sulphuric acid, which is most injurious
to rubberized balloon fabrics ; for this reason the
vitriol process is not favored when it is prac-
ticable to secure hydrogen by other processes,
but if it must be used then special precautions
should be taken such as multiplying the number
of washers and purifiers and frequently chang-
ing the lime in the purifiers. Fresh unslaked
lime is used in the purifier to absorb the moisture
charged with traces of sulphuric acid which
passes out of the hot generating tanks. The
lime (CaO)' has a great affinity for water (CaO
-(- H2O ^ Ca (011)2) changing it to slaked
lime (calcium hydroxide) upon absorbing the
water. The lime also combines chemically with
the sulphuric acid forming calcium sulphate

(2CaO + H2SO4 = CaSO, + Ca(0H)2).

Greater purity of hydrogen can be insured
when the weight of apparatus is unimpor-
tant, as in permanent installations, by add-
ing in series more purifiers containing chemical
substances such as Caustic Soda (NaOH) and
Calcium Chloride (CaCl2) both of which have
property of absorbing moisture which is carried
along with the hydrogen.

In order to determine the quantities of chem-
icals required to produce a certain quantity of
hydrogen by any jjrocess, apply the atomic
weights of the elements in the chemical equa-
tions in the manner shown below; for example.

making the object of the computation 1000 cu.
ft. of hydrogen, it is necessary to determine first
the number of cubic feet of hydrogen in one
pound of the gas. This is found to be about
178 feet by taking 12.388 cu. ft. of air as weigh-
ing one pound and considering air as 14.4 times
heavier than hydrogen, which figures are suffi-
ciently accurate for this purpose.

Example : Fe + H2SO4 = FeSO* + H2
55.84 (2 + 32 + 64)= 152 + 2

Then by Proportion:

3256 cu. ft. H : 1000 cu. ft. :: 55.84 lbs. Fe, : X
X = 157 lbs. iron

Similarly for sulphuric acid, 356 : 1000 : : 98 X
X = 275 lbs.

It is seen from the foregoing that 157 lbs. of
iron and 275 lbs. sulphuric acid are theoretically
required to produce 1000 cubic ft. hydrogen, but
in estimating or purchasing these materials it is
always advisable to increase the amounts by at
least 5 and better 10 per cent, to allow for im-
purities in chemicals, incomplete chemical ac-
tion, and losses of gas due to generators and
pipes not being gas-tight in improvised ap-
paratus.

The atomic weight of zinc is 65 and by a sim-
ilar chemical equation it is found that theoreti-
cally 182.5 lbs. of zinc and 275 lbs. of sulphuric
acid are required to produce 1000 cubic feet of
hydrogen.

tkiSiitiSmh&fii

L .--^^

jrMr

1^6^^ '.jfe^i^MitoWaisSfcai

finS'^ inii d?9inK3

JiKqoiBfi

BmlSra

The motor transports, including hydrogen carriers of a U. S. Army balloon company photographed at Umaha. (Passed by the

Censor.)

170

TEXTBOOK OF MILITARY AERONAUTICS

Portable hydrogen gas plant constructed for the chief engineer-
ing department of the Imperial Russian War OfBce.

Zn + HoS04 . Aq==ZnS04 . Aq + 2H.

65+(2 + 32 + 64) = (65 + 32 +64) +2.

At least 5 per cent, should be estimated above
the theoretical amounts, for supplies of zinc and
acid. Zinc usually contains some lead as im-
purity; the lead is not objectionable, but on the
contrary, is said to assist in promoting rapid
chemical combination due to galvanic action.

Using only the quantities of iron and acid ac-
cording to the theoretical computation and as-
simiing the cost of iron turnings at 2 cents per
pound and acid at 3 cents per pound, the cost of
materials alone to produce 1000 cu. ft. hydrogen
would be $11.39.

Electrolytic Method

Hydrogen of greatest purity is obtained in
commercial practice by the electrolysis of water,
the hydrogen collecting on the negative elec-
trode and the oxygen on the positive electrode
where current enters the cell. A direct current
of electricity is passed through water in a suit-
able cell which is provided with pipes for col-
lecting both gases. The electro-chemical equiv-
alent of hydrogen is .0000104 grams per cou-
lomb which in larger units amounts to nearly 15
cubic feet of hydrogen for a current of 1000
ampere hours. The theoretical electromotive
force required to dissociate water into its con-
stituent elements is 1.47 volts between elec-
trodes. Therefore, due to the internal resist-
ance of the cell, if the voltage required is 2, then
the computation shows that one kilowatt hour of

electric power will produce 7^/2 cubic feet of
hydrogen.

The internal resistance of cells increases with
the distance between the electrodes, and de-
creases as the size of the electrode increases. It
varies also depending upon the nature and spe-
cific gravity of the electrolyte in the cell.

Pure distilled water is a very poor conductor
of electricity and extremely high E.INI.F. would
be necessary unless the conductivitj^ is improved
by adding suitable chemicals to the water. Or-
dinarily, pure caustic soda (NaOH) is used,
bringing the solution to specific gravity between
1.2 and 1.25 at 60° F. It is found experiment-
ally that 2^/4 pounds of chemicallj^ pure caustic
soda are required to bring one gallon of distilled
water to 1.25 specific gravity. This is about 17
per cent, caustic soda and is the point at which
the solution has the greatest conductivity.
Adding more caustic soda increases the internal
resistance. Caustic potash (KOH) may also
be used for electrolyte but larger quantity is re-
quired and the present cost is much greater than
that of caustic soda.

There are two general types of construction
for electrolizers, one being the unit type which
consists of separate cells, each containing the
positive and negative electrodes, connected elec-
trically in series; the other general type being
called by various names, "bi-polar," "multiple-
plate," and "filter-press" types. These electro-
lizers are usually constructed by assembling
large plates very close together separating the
positive and negative electrodes by sheets of as-
bestos; where 110 volt power is available these
generators have 60 pairs of plates. The ad-
vantage of the multiple plate type over the unit
cell type is principally lower first cost and less
floor space required; the disadvantages being
in greater maintenance cost and difficulty of
preventing leakage of gas. ^lost of the electro-
lizers made in the United States, both unit type
and bi-i)olar, utilize a special weave of asbestos
cloth as separator for the hydrogen and oxygen
within the cell. The foreign-made cells at Fort
Omaha have a very fine wire gauze to separate
the gases.

The quantity of hydrogen produced by this
method is proportional to the amjjerage passed

HYDROGEN FOR MILITARY PURPOSES

171

through the cell. For American made electro-
lizers the current varies from 35 amperes to
1000 amperes, and for the Siemens cells at Fort
Omaha the normal current is 1500 amperes.
The E. M. F. required for each unit cell or for
one pair of plates in the multiple type will aver-
age 2 volts, but depends entirely upon the in-
ternal resistance of the cell, which in turn de-
pends upon the size of the electrodes, distance
between them, nature and specific gravity of the
electrolyte and the temperature. It is observed
in practice that in starting the plant when cells
are cold the E.M.F. per cell is often more than
3I/2 volts, which reduces to less than 2 volts after
the cells become hot.

As the water in the cells is converted into gas,
it must be replaced by pure distilled water.
The quantity being 5.76 gallons for 1000 cubic
feet of hydrogen. It is seldom necessary to add
caustic soda to the solution and then only
enough to replace the very small quantity which
is carried off from the cells by the moisture with
the hot gases, but even this vapor may be con-
densed and recovered to some extent by mois-
ture traps of various kinds.

Most manufacturers of electrolizers in the
United States claim an output of 7V2 cubic feet
of hydrogen per kilowatt hour. As shown in
the preceding paragraphs, this means an E. M.
F. of not to exceed 2 volts per cell. When it is
possible to secure electric power at 1 cent per

K. W. H. the cost of 1000 cubic feet or hydro-
gen for power alone is $1.57 (assuming motor-
generator efficiency of 85 per cent., and electro-
lizer efficiency of 7^ cubic feet hydrogen per
K. W. H.).

The electrolytic plant installed by the armj'
at Fort Omaha in 1908 consists of 30 large cells
made by Siemens Bros. Company, Ltd., Lon-
don, the normal current being 1500 amperes
and the voltage varying fi'om 4 to 2.2 per cell,
depending on temperature. The temperature
should be maintained at 150 degrees F.
Higher than this is likely to damage the insula-
tion and produce an excess of moisture with the
gas. Lower temperature increases the internal
resistance and cost of electric power. Each cell
produces 23.3 cubic feet of hydrogen per hour,
a total of 699 cubic feet per hour for the 30
cells, equivalent to 16,776 cubic feet per day
of 24 hours for the plant.

Silicol Process

The production of hydrogen by dropping
ferro-silicon into hot caustic soda is, in the
French and British Armies, known as the
"silicol" method; in Germany it is called the
Schuckert process, and for manj' j'ears the de-
tails of it were carefully concealed.

The chemical reaction producing hydrogen is
between silicon and caustic soda without any

• .f '*t i^. vl -V -^j^jatSl! . .

A batteiy of hydrogen gas
cylinders attached to supply
pipe of balloon being filled.

172

TEXTBOOK OF MILITARY AERONAUTICS

change in the iron. The following chemical
equation will serve to explain the process:
Si + 2XaOH + 2H2O = NaaSiOs + 4H. +
HoO. In Germany it was customary to use
pure or nearly pure silicon. In France this
method was developed for the military service
by Capt. Le Large and Dr. Jaubert ; the gene-
rating apparatus being designed in three types ;
viz: Auto truck transportable size, semi-
fixed and for permanent installations. Ferro-
silicon is used, being more easily secured
and at less cost than pure silicon as in
the Schuckert generators. The steel indus-
try in this countrj' uses large quantities of
ferro-silicon containing 50 to 75 per cent, silicon.
Experiments have shown that more satisfactory
chemical action is secured by having the silicon
content 80 to 85 per cent. Commercial caustic
soda of 97 per cent. NaOH is suitable.

Except in very cold weather the mixing of
caustic soda with water produces sufficient heat
to start the chemical combination of silicon and
soda. It is necessary to agitate the solution
constantly to secure best results and avoid sud-
den generation of large quantities of gas of ex-
plosive violence. The solution resulting from
the chemical combination is sodium silicate,
which may be easily drawn off at the bottom of
the mixing tank.

According to the chemical equation, the pro-
duction of one thousand cubic feet of hydrogen
would require 39.6 pounds of pure silicon and
112.3 pounds of pure caustic soda. The actual
quantities which should be supplied depend

German railway truck with itccl cylinders.

upon the silicon content of the ferro-silicon and
the percentage of purity of the caustic soda.
An experiment conducted for the army deter-
mined that 58 pounds of 80 per cent, ferro-sili-
con and 125Y2 pounds caustic soda would pro-
duce 1000 cubic feet hydrogen. Ferro-silicon
at 15 cents per pound and caustic soda at 3 cents
per pound would bring the total cost for ma-
terials to $12.46 per 1000 cubic feet.

Ferro-silicon may be stored without deteriora-
tion by moisture and without any special pre-
caution for its care. The caustic soda must be
protected from moisture and is usually supplied
in air-tight drums containing 100 pounds.

In connection with silicol generators, there
are required washers and purifiers to remove
from the gas the hot vapors carrying caustic
soda solution. Field generators of this process
should alwaj^s be set up for operation near a
stream or other ample supply of water. It is
possible to design the generating equipment
with radiators for cooling the circulating water
for situations where water economy is important.

Iron Contact Process

The iron contact process for production of
hydrogen is often referred to as the regenera-
tive steam and iron and method, the principle
being that when steam passes over red hot iron
it is decomposed into its constituent elements,
the iron absorbing oxygen from the steam and
the hydrogen collected. The chemical reaction
is represented by the equation : 2Fe -f 3H2O
= Fe203 + 6H. To utilize this principle
commercially, it is necessary to reduce the
ferric-oxide back again to metallic iron which
can be done by passing carbon monoxide over
the iron oxide, the carbon monoxide (CO) tak-
ing an atom of oxygen from the iron becomes
carbon dioxide (COo) represented by the fol-
lowing equation:

SCO + FejOs = 2Fe + SCO^

The conmiercial equipment for production of
hydrogen by the iron contact process utilizes
the well-known water-gas process for making
the carbon monoxide which is needed to reduce
the iron from the oxide to pure metallic state.

HYDROGEN FOR MILITARY PURPOSES

173

Close view of the carriage of a British
Blimp.

The water-gas generator is filled with coke
which is heated to redness by a blast of air for
a very brief period. When steam is turned on
to this red hot coke, it is decomposed, the hy-
drogen freed from the oxygen is combined with
the carbon of the coke forming carbon monox-
ide (CO). The water-gas consists principally
of hydrogen and carbon monoxide, but must be
passed through washers and purifiers to remove
dust and particularly sulphuretted hydrogen.
Sulphur is removed by passing the gas over
trays of iron. The purified water-gas, usually
referred to as "blue gas," is then stored in a
holder, available for use as reducing agent.

After steam has passed over the red hot iron
for a few minutes, the temperature is lowered to
such an extent that it no longer decomposes the
steam and it is then necessary to raise its heat
and at the same time change the ferric oxide
to metallic iron by turning the blue gas into the
ovens. The period of heating the iron and re-
ducing the oxide requires about twice the
amount of time for the hydrogen production
phase.

Temperature is a most important factor and
must be constantly watched in all phases of the
process. In the water-gas generator, if the
temperature is too slow, carbon dioxide is
formed instead of carbon monoxide. In reduc-
ing the ferric oxide, if the temperature is not

sufficiently high the reduction will be only from
the ferric oxide FcaOs to Fe^Oi or at still lower
temperature to FeO instead of to the pure
metallic Fe.

The reduction ovens are originally filled with
hematite (Fe203) which should be as porous as
possible in order to expose greater surface to
the action of the steam and carbon monoxide,
and this ore should be free from sulphur com-
pounds and other impurities. It is necessary
to replace the ore in the ovens about every six
months.

The iron contact process was developed long
ago by Coutelle and perfected by Giffard in
France, then developed commercially in Eng-
land by Lane using several retorts for the iron.
In Germany it was further developed by A.
Messerschmitt, utilizing one large regenerative
oven instead of many small retorts. The Mes-
serschmitt regenerative oven is patented in the
United States. The patents relate only to the
oven and retorts; the steam and iron process is
not patented. At least two firms in this coun-
try install iron contact plants, which produce
3500 cubic feet of hydrogen per hour. Plants
of this size and type are now under construction
for the Navy Department at Pensacola, for the
Army at Langley Field, and for a private firm
near Akron, Ohio.

Hydrogen produced by the iron contact proc-

174

TEXTBOOK OF MILITARY AERONAUTICS

Filling cylinders on the railway truck.

ess has a purity of at least 98 per cent. The
impurities consist principally of nitrogen and
carbon dioxide which have no deleterious effect
on balloon fabric, nor are these gases inflam-
mable. It is claimed that hydrogen can be pro-
duced by this process from 25 cents to 75 cents
per thousand cubic feet.

Aluminum Caustic Soda Process

During the war between Russia and Japan
both armies used field hydrogen generators em-
ploying the chemical reaction of alkaline hy-
drates upon aluminum. Sodium hydrate
(XaOH) ordinarily known as caustic soda, is
preferred to the potassium hydrate on account
of the lower cost of the soda. The chemical
reaction taking placfe is represented by the fol-
lowing equation:

6XaOH + 2 Al = AI2 ( OXa ) « + 6H

The generating apparatus was constructed in
two types, one of small size installed on vehicles
for rapid transportation, and a larger size called
"semi-fixed." An iron basket is filled with
aluminum sqrap, lowered into the solution of
caustic soda, the cover being immediately
clamped to make it gas tight. The gas passes
from the generator to a washing and cooling de-
vice which removes the traces of alkaline matter.
In the generator the aluminum is attacked by
the sf)da solution with great energ>', the gas com-
ing off rapidly and the liquid heating to the

boiling point, but as the proportion of free soda
in the solution diminishes, the rate becomes
slower. In order to finish the gas production
without delay, the generator is charged with
caustic soda considerabh^ above the theoretical
requirement.

According to the theoretical computation, it
is found that to produce 1000 cubic feet of hy-
drogen there are required 224 pounds of caustic
soda and 51 pounds of aluminum. With caus-
tic soda at 3 cents per pound and aluminum at
50 cents per pound, the cost of the one thousand
cubic feet of hydrogen by this process is $32.22.
The actual quantity of materials to be carried
will be considerably in excess of 275 pounds and
the cost per thousand more than the foregoing
computation indicates, on account of the neces-
sity for using an excess of caustic soda and the
fact that commercial caustic soda contains im-
purities, the most common grade containing only
77 per cent, sodium hydrate.

The aluminum and alkali method has the ad-
vantage of requiring about 20 per cent, less
weight of material than the viti-iol process and
both materials being dry are easily transported
without the especial care which is necessary for
the transportation of sulphuric acid. Further-
more, the hydrogen produced is of greater pur-
ity, does not contain volatile hydrocarbons, nor
the dangerous gases produced by combinations
of hydrogen and arsenic.

U. S. patent was issued in September, 1901,
for a modification of the aluminum-caustic-soda
process. The inventor prepared the material
by pouring molten caustic soda into a mass of
aluminum in the form of powder, filings, or
turnings, which was thoroughly mixed before
the mass cooled. This mixture of material
must be kept in sealed containers to avoid de-
terioration due to moisture in the atmosphere.
When the mixed substance is placed in water
the chemical reaction produces sodium alumi-
nate and free hydrogen, probably according to
the following equation :

2A1 + 2XaOH + xH^O = NasAljO* +
xH.O + 8H2
or 2A1 + eXaOH -f xH,0
= NaeAUOa + xHsO + 8H,

HYDROGEN FOR MILITARY PURPOSES

175

Hydrolithe

"Hydrolyte" is calcium hydride (CaHz)
manufactured by heating pure metalhc calcium
in retorts containing hydrogen. To produce
hydrogen it is only necessary to drop the gran-
ulated hydrolythe into water. Generating
equipment similar to the ordinary acetylene gas
outfits are suitable. The reason hydrolythe is
not more extensively used is on account of its
high cost. About ten years ago the Signal
Corps purchased a sufficient quantity to con-
duct experiments, which confirmed all claims
for it, but chemical manufacturers in the United
States do not produce it at present. It will be
seen from the following chemical equations that
only 59 pounds of hydrolythe are required to
produce 1000 cubic feet of hydrogen:

CaH2 + H2O = CaO + 4H.

At 80 cents per pound for hydrolythe the cost
of 1000 cubic feet of hydrogen by this method
would be $47.20.

Pure sodium or lithium dropped in water will
produce hydrogen and it is possible to make
hydrides of lithium the same as calcium which

will similarly produce hydrogen upon contact
with water. On account of the light weight of
lithium this would be particularly desirable for
field hydrogen generation, and experiments are
now in progress to determine whether it is prac-
ticable to manufacture lithium hydride at rea-
sonable cost.

Dropping pure lithium in water would the-
oretically require only 40 pounds to produce
1000 cubic feet of hydrogen: 2Li + H2O =
Li^O + 2H.

And of lithium hydride 221/2 pounds would
produce 1000 cubic feet hydrogen 2LiH +
H.O = LiaO + 4H.

About ten years ago an American manufac-
turer proposed the use of lead compounds hav-
ing great affinity for water known as "Hydrone
A, B, and C," and experiments were conducted
by the Signal Corps. It developed that the
chemical reaction upon dropping the substance
into an alkaline solution was so violent that the
oxygen of the air above the generating tank
would burn the hydrogen, — the ignition being
due to heat of the chemical action. This diffi-
culty was overcome by manufacturing a lower
grade which evolved hydrogen slowly. The

One of the Goodyear "Blimps." Photo passed by the Censor.

176

TEXTBOOK OF MILITARY AERONAUTICS

A military balloon ascending.

low-grade material was first dropped into the
generator until the escaping gas had carried
with it all oxygen above the water, then the
high-grade substance was fed into the generator.
On account of the extreme care that was neces-
sary to avoid explosions with this method and
the considerable weight of the hydrone, its fur-
ther development for field hydrogen generation
in the army was discontinued. One pound of
hydrone produced only 2.88 cubic feet hydro-
gen at a cost of QYo cents per foot.

Hydrogenite

This hydrogen process is a modification of
the "silicol" process already described. The
chemical substances and reaction are the same
as the silicol, but the materials are prepared
and used in somewhat different manner. Pul-
verized ferro-silicon and caustic soda properly
proportioned are thoroughly mixed and pre-
served in hermetically sealed cartridges, each
containing .50 kilograms.

The field generators to use these cartridges
consist of metal container slightly larger than

the cartridge, having a lid which can be clamped
down gas tight. After placing the cartridge in
the apparatus, the top of the can is opened and
the mixed powders ignited. Around the inside
of the cylindrical burning oven in which the
cartridge is placed, is a trough to contain a
measured quantity of water. The heat pro-
duced by the burning of the chemicals quickly
converts this water into steam, the silicon, soda,
and water combining as in the previously shown
equation describing silicol method.

Ignition may be started by a fuse or taper in-
serted in the powder or by placing on top a
small quantity of some easily combustible
powder in order to produce sufficient heat in
one spot to start the combustion. The hydro-
genite burns rapidly and without flame, like
tinder; a cartridge of 50 kilograms being con-
sumed in about ten minutes.

When the mixture is first ignited, the air in
the chamber and products of combustion are
permitted to escape until the pure hydrogen ap-
pears. The gas is passed through washing and
cooling purifiers before being used.

It is learned that even with the greatest care
generators ai'e frequently destroyed by explo-
sions, for which reason the process is not in gen-
eral use.

Hydrogen from Water-Gas

A German chemist developed and advocated
some years ago the production of hydrogen for
aeronautical purposes by first manufacturing
water-gas in the usual manner, which consists
principally of hydrogen and carbon monoxide,
passing the water-gas over red hot calcium car-
bide in the form of powder. The hot calcium
carbide decomposes the carbon monoxide form-
ing lime (CaO) and leaving carbon in the form
of crystalline graphite. The inventor claims
that minor impurities in the water-gas are al-
most entirely removed in the reaction, produc-
ing hydrogen of 99 per cent, purity. The re-
port further stated that generating equipment
was devised to produce 70,000 cubic feet of hy-
drogen daily.

Hydrogen may also be separated from water-
gas or coal gas by the fractional refrigeration

HYDROGEN FOR MILITARY PURPOSES

177

process. Hydrogen liquefies under pressure at
lower temperature tlian other common gases,
so that from illuminating gas having a consid-
erable percentage of hydrogen it is possible to
cool and compress it with liquid air apparatus,
drawing off first all other gases as they liquefy
and leaving the hydrogen. This method is not
in general use for commercial production for
the reason that other methods offer more simple
and more economical means of securing hydro-
gen.

The Electrical Review (Vol. 40) reported
that M. D'Arsonval passed coal gas previously
cooled to minus 80° C. through a Linde liquid
air machine, obtaining 3500 cubic feet of hydro-
gen per hour, expending 12 to 15 horse-power.
Assuming coal gas to cost $1 per thousand and
containing 50 per cent, hydrogen, the cost of
material would be about $2 per thousand cubic
feet hydrogen, to which must be added approxi-
mately 60 cents per thousand for power, plus
cost of expert attendance.

Aluminum-Potassium Cyanide Process

A French chemist a few years ago advocated
the generation of hydi'ogen for aeronautical

purposes by mixing aluminum filings with pul-
verized bichloride of mercury and potassium
cyanide. After these ingredients are thor-
oughly mixed hydrogen will be produced by
adding water. The powder has a density of
1.42 and must be kept in hermetically sealed
cans. It is stated that experiments indicated
187 pounds of this material were required to
produce 1000 cubic feet of hydrogen. The
chemical reactions which take place should
properly be represented by three or four stages,
but may be sufficiently explained by the follow-
ing single equation:

6KCN + 6H2O + 4A1 + 3 HgCla =
2K3AIO3 + 12H + 3Hg(CN)2 + 2A1C18

Acetylene Process

In 1901 Mr. H. Houbon, a resident of Eng-
land, invented and patented a process for mak-
ing pure hydrogen from acetylene. He com-
pressed the acetylene to 5 atmospheres in a
Caillet steel bomb and ignited it by electric
spark. The carbon precipitates in the form of
fine soot leaving the pure hydrogen. It is
stated that the process is without danger and

A British "Blimp" passing over an anti-aircraft post.

178

TEXTBOOK OF MILITARY AERONAUTICS

calcium carbide for producing acetylene is very
cheap, but it is not known that this process has
ever been perfected for producing hydrogen in
large quantities for aeronautical service.

By computation it is found that 180 pounds
of calcium carbide are required to produce 1000
cubic feet of hydrogen by this method.

C2H2 + Heat = 2C + 2H

Iron and Water Process

Recently an article in a German technical
journal described a new method for securing
compressed hj'drogen of great purity. So far
as known it has been employed only in labora-
tories, but it may be developed later on a com-
mercial scale.

Powdered iron is mixed in water in a vertical
steel cylinder, the liquid being subjected to a
pressure of 300 atmospheres (5,410 pounds per
square inch) and the temperature raised to 350°
C. The chemical reaction that takes place is
sufficiently explained by the following equa-
tion :

2Fe + 3H2O = Fe^Os + 6H

from which it is seen that under this great heat
and pressure the iron combines with the oxygen
from the water, and the hydrogen may be re-
moved at the top of the cylinder already com-
pressed for storage in cylinders. The iron ox-
ide may be easily reduced again to metallic iron,
which is facilitated by its porous condition, due
to the peculiar manner in which it is oxidized.
Hydrogen obtained is said to have 99 per cent,
purity, which can be further increased to 99.95
per cent, by being passed over charcoal. When
iron contains sulphur, the sulphur is not at-
tacked, but any carbon content in the iron is
converted into carbon monoxide.

Silico-Acetylene Process

The silicides of calcium, barium and stron-
tium (CaSi2 : BaSi2 : SrSi2) are made in the

electric furnace similar to the manufacture of
calcium carbide. When calcium silicide is
added to aciduated water, it is decomposed,
leaving sihco-acetylene in solution; the calcium
oxide is precipitated. The solution is drawn
off and evaporated, leaving yellow ciystals of
sihco-acetylene SiaHa. When these crystals
are added to alkahne solution such as caustic
soda or potash, the silico-acetylene is decom-
posed, evolving hydrogen. It is reported that
163 pounds of silico-acetylene are required to
produce 1000 cubic feet of hydrogen.

Decarburation of Oils

About four years ago the Scientific American
described equipment developed by the German
Army for the generation of hydrogen by the
method of decarburizing hydro-carbon oils.
The apparatus was designed for installation on
two railway cars, the main part of the equipment
consisting of two gas producers. To fire up
these producers to the proper heat requires from
one to two hours.

The producers are filled with coke which is
heated to redness by air-blast. Crude petro-
leum or any petroleum distillates are first va-
porized and then passed through the producer
ovens containing the hot coke, which decom-
poses the oil. After about twenty minutes the
coke has been reduced in temperature so much
that it is necessary to heat it again to redness
by hot air blast. This requires only two or
three minutes.

The gas produced is passed through water
scrubbers and purifiers to remove sulphur. It
contains considerable carbon monoxide which
is removed by passing the gas through an oven,
the details of which process are not stated. The
resultant gas is said to be OS.! per cent, hydro-
gen, 1.2 per cent, nitrogen, and 0.4 per cent,
carbon monoxide, and to have a specific gravity
between 0.087 and 0.092.

Courtesy Underwood & Underwood.
Group of students seated around big relief map.

Photo passed by the Censor.

CHAPTER XIV

TRAINING AVIATORS FOR THE UNITED STATES ARMY; HOME AND

FOREIGN SERVICE

The training of aviators for the United States
Army, for home and foreign service, is con-
ducted by the Organization and Training Sec-
tion of the Aviation Division, Signal Corps,
whose offices are in the War Department,
Washington, D. C.

According to a recently issued official state-
ment, this Section deals with the organization
of aviation school squadrons and standard
aerosquadrons, the latter composed of gradu-
ated Reserve jSIilitary Aviators.

There are but a few officers with the title
"Military Aviator " and "Junior Military Av-
iator." These are in administrative positions.

This Section has nothing to do with training
of men for aerostatic work, which is handled by
the Balloon Division.

The Aviation Division of the Signal Corps
is composed, originally, of officers and enlisted
men of the Regular Army, limited by law to a
definite number. Additional personnel is pro-
vided through the Signal Officers' Reserve
Corps, the Signal Enlisted Reserve Corps, and
the employment of civilians in instructive, ad-
visory, administrative, or other capacities.

Civilians may be employed (1) as such; (2)
by passing standard physical and mental ex-
aminations and by going through the routine

Practically the entire new flying personnel is of joining the Signal Officers' Reserve Corps,
to be composed of Reserve Military Aviators, in which event, if satisfactory, they may be

179

180

TEXTBOOK OF MILITARY AERONAUTICS

given commissions therein commensurate in
grade with their attainments and duties, as fol-
lows:

(a) Non-flj'ing duty,

(b) Flying duty (as pilots or observers),

The Organization and Training Section also
handles original applications for commissions
in the S.O.R.C. from civilians. Regular
Army or National Guard officers and men are
needed as supply, engineer, or field-inspector
officers. Opportunity is afforded by personal
interview to obtain first-hand knowledge of the
particular attainments of each man. If pre-
liminary investigation is satisfactory, the ap-
plicant fills out his blank and is turned over to
the Personnel Division, which attends to the
routine of physical and mental examination.
Upon the obtaining of his commission he is as-
signed to such place as his services are required.

Form of letter of application for examination
for commission in Officers' Reserve Corps.

[Under section 37, Act of June 3, 1916.]

I have served

years in

19-

Sir: I have the honor to apply for examina-
tion for a commission as ^ aviation section,

in the Signal Officers' Reserve Corps, organized
under the authority of Congress.

1 Insert grade, first lieutenant, captain, or major.

I have pursued a regular course of instruc-

tion for

years m

I graduated in the year

from

after having creditably pursued the course of
military instruction therein provided.

I was born , , at , and

am "• a citizen of the United States.

A.g& . Color . Height .

Weight .

My business is .

My experience is .

I inclose letters of recommendation and ad-
dresses of three citizens who know me as fol-
lows : .

Respectfully,

Permanent post office address

The correctness of the statements above made

was sworn to and subscribed before me

, 19—.

The duties of the Aero-Personnel Division
consist of matters affecting the commissioned
and enlisted men of the Aviation Section of the
Signal Corps, which may be more conveniently
termed the Army Air Service. All communi-

2 Insert service in the Regular Army of the United States, or
Volunteer forces of the United States, or Organized Militia of
any State, Territory, or District of Columbia; also state in what
capacity.

s Insert name and location of the school or college.

* Insert the name and location of the educational institution.

5 Insert "not" if in accordance with fact.

8 Oath to be taken before, and signature to be made by, officer
authorized by law to administer oaths.

Group of army aviation students at one
of the training fields.

TRAINING AVIATORS FOR UNITED STATES ARMY

181

students learning the assembling ot aeroplanes at a University, somewhere in America

cations to the Chief Signal Officer, or higher
authority, that are concerned with the subject
of aviation personnel must pass through this
Division, except when such communications
deal with civilian employees.

The personnel of the Army Air Service com-
prises the following groups:

(a) Enhsted men of the Regular Army.

(b) Signal Enlisted Reserve,^ throughout
this chapter referred to as "Enlisted Reserve
Proper."

(c) Men (flying duty) enlisted temporarily
in the Signal Enlisted Reserve in order to ob-
tain training for a commission in the Aviation
Section of the Signal Officers' Reserve Corps.
(Throughout this chapter they are referred to
as the "Enhsted Reserve.")

(d) Reserve Officers (flying duty).

(e) Reserve Officers (non-flying duty).

(f) Officers (of the Regular Army).

The Aero-Personnel Division is also con-
cerned with two other groups of men :

(g) Enlisted applicants of the Regular
Army for transfer to the Air Service.

(h) Commissioned applicants of the Regular
Army for detail to the Air Service.

(a) Present provisions in regard to the first
of these groups continue as now prescribed by
law and Army Regulations. The Aero-Per-
sonnel Division has charge of the records of en-
listed men of the Regular Army.

(b) The purpose of the "Enlisted Reserve
Proper" has been to secure a body of trained

1 Inasmuch as all enlistments are for the period of the war
and the policy of the office is to accept men for the Regular
Army only, paragraph (b) is modified to this extent.

mechanicians, machinists, electricians, chauf-
feurs, and other qualified men, who may be
quickly called in time of need. Cards giving
the home addresses and information about the
enlistments of such reservists are kept in the
Aero-Personnel Division. Similar informa-
tion is in the service record of each reservist, in
the hands of the department commander in
whose territorial jurisdiction he resides. No
more enlistments in this group as reservists are
being made at present, there being no desirabil-
ity during wartime to increase the number of
reserves not on active duty. At date of writing
the entire personnel of this group is being called
into active service by department commanders
immediately upon enlistment. They are as-
signed to aviation stations and placed in train-
ing.

(c) The enlisted reservists who are appli-
cants for commissions as reserve officers, flying
duty, and are enlisted in the Signal Enlisted Re-
serve Corps simply for the purpose of prelimi-
nary training prior to receiving their commis-
sions, comprise an extremely important group.
From their number will come almost exclusively
the aviators of the Army Air Service. The
procedure in regard to the enlistment of these
men is in the hands of the Aero-Personnel Di-
vision. All applicants for commission in the
Aviation Section of the Signal Officers' Reserve
Corps must forward their applications to the
Aero-Personnel Division for approval or disap-
proval. If the application is approved, its
sender is given an examination to determine his
physical condition, and a second examination to
test his moral, professional, and educational

182

TEXTBOOK OF MILITARY AERONAUTICS

qualifications for a commission. Boards to give
the complete examinations are situated at each
of the Schools of ^lilitary Aeronautics; also at
the several Signal Corps flying schools in the
different states and at Washington.

If the candidate is successful in passing these
examinations, he is reexamined with a view to
enlistment as first-class private in the Signal
Enlisted Reserve, and is then either sent home
with a certificate of enlistment to await further
orders, or is sent immediately to one of the
"ground schools" (Schools of Military Aero-
nautics) for instruction.

From this time until the receipt of his commis-
sion the candidate is under the jurisdiction of:
First, the Schools of Military Aeronautics Di-
vision; and later the Organization and Train-
ing Division. The Aero-Personnel Division
asks for the transfer to the "ground schools" of
suitahle students on duty at the Federal Re-
serve Officers' Training Camps. Such re-
quests, if recommended, are made weekly.

(d) Upon successful completion of the fly-
ing-school course, the candidate is commissioned
as a reserve officer, whereupon his relation to the
Aero-Personnel Division becomes like that of
a regular officer of the Air Service.

Competent civilian flyers, who pass the physi-
cal and mental examinations and are satisfac-
tory otherwise, may at once be commissioned in
the Signal Officers' Reserve Corps and ordered
to active duty.

(e) Civilian apj)licants for commissions in
the S. O. R. C. for non-flying duty in capacities
such as engineer, supply or other officer, may
take mental and physical examinations (the lat-
ter less rigid than that for flying duty), and if
qualifications are satisfactory, may be commis-
sioned and ordered to active duty.

America's future airmen are here
shown ]iracticing tlie Morse Interna-
tional Code as one of tlie first steps in
masterinjr the science of radio transmis-
sion which they will soon he using over
the German trenches in France. Photo
passed hy Censor.

(f) All communications in regard to officers
of the Arm}' Air Service pass through the
Aero-Personnel Division. Similarly, all orders
for officers of the Air Service that are requested
from the Adjutant-General pass through this
division. Complete military records of officers
are also kept there.

(g) Applications of enlisted men of the Sig-
nal Corps proper, or of other staff corps or de-
partments or arms, for transfer to the Air Serv-
ice should be approved by the Aero-Personnel
Division before orders are issued for such trans-
fer.

(h) Any officer of the Regular Army, who is
an applicant for detail to the Air Service, has his
military record and correspondence concerning
him kept by the Aero-Personnel Division while
he is undergoing training at the Signal Corps
flying schools. Upon detail to the Air Service,
the status of such an officer in relation to this
division is precisely like that of other officers of
the Army Air Service.

In all cases application for enlistment, trans-
fer, detail, or commission, is made direct to the
Aero-Personnel Division.

Schools of Military Aeronautics
(Ground Schools)

Successful candidates for flying duty are di-
rected by the Aero-Personnel Division to one of
the ground schools located at the following in-
stitutions :

Massachusetts Institute of Technology, Bos-
ton, Mass.

Cornell University, Ithaca, New York.

Ohio State University, Columbus, Ohio.

University of Illinois, I''"rbana. Illinois.

Texas University, Austin, Texas.

TRAINING AVIATORS FOR UNITED STATES ARMY

188

One of the Army aviation training fields, showing Curtis JN-4 scJiool planes. (Committee on Public Information.)

University of California, Berkeley, Calif.

Princeton University, Princeton, N. J.

Georgia Institute of Technology, Atlanta,
Ga., Jolm Hopkins University, etc.

(Additional institutions are being added to
this list at date of writing.)

Upon arrival, the S. M. A. Division is advised
thereof, with a list of candidates, which list is
kept by the S. M. A. Division in cooperation
with the Organization and Training Section.
Now the students are under the charge of the
S. M. A. Division,

Here the students serve eight weeks with the
pay of a first-class private, about a dollar a day,
and with the allowance of a dollar a day for
rations. Quarters are provided in barracks.
The candidate upon entering the Ground
Schools of Military Aeronautics becomes a ca-
det. He is assigned to a "Junior Squadron,"
where he remains for three weeks; then he is
transferred to a "Senior Squadron."

Each squadron consists of between twenty to
thirty cadets in charge of a first sergeant.

At these ground schools the cadets are given
a general course in military discipline and drill,
as well as intensive instruction in aeronautical
engines, telegraphy, machine-guns, bombing
and fighting, aerial observation and cooperation
with artillery and infantry, including map-
reading, contact patrol and reconnaissance;
army regulations and military subjects; flying
with meteorology, instruments, compasses, pho-
tography; rigging, care and repair of aero-
planes, engines and cameras. Guns and other
apparatus are provided for practical study.

Upon completion of this course the students
are assigned through the Aero-Personnel Di-
vision to the aviation school squadrons, as noted
under "Organization and Training."

The daily schedule at the ground schools of
military areonautics is more or less as follows:

Reveille, 5 :35 a. m. First call, 5 :40. All
calls are by bugles, the same as in the army.
Assembly is blown at 5 :50 A. M., when all cadets
must be in ranks in their respective places. On.
all assembly calls the first sergeant of each
squadron orders his men to fall in. Then he
receives his corporal's report of "lates" or "ab-
sentees," about faces to the officer of the day,
and reports concerning lates or absentees from
his squadron; whereupon the officer of the day
commands the senior first sergeant or cadet cap-
tain to take charge of the men for calisthenics.

The senior cadet sergeant marches all the
squadrons to the court, and when they have
taken their respective places leads them through
ten minutes of calisthenics. At the end of this
time the squadrons are placed in command of
their respective sergeants, the two senior squad-
rons being marched immediately to mess, the re-
maining squadrons returning to the quadrangle,
awaiting their turn for mess.

The mess takes about an hour for each squad-
ron. At 6 :55 A. M. first call for drill is blown.
At 7 A. M. assembly is blown, whereupon the
men are marched to the drill field and given one
hour of military drill. As the men in this
school are training to become aviator officers, a
full course in military drill is not required, the
reason being that the man getting his commis-

184

TEXTBOOK OF MILITARY AERONAUTICS

sion wiU have hardly any enhsted men under
him to drill.

Saturday:

8-9 A. M.

9-10
10-11

Study Hour

Reconnaissance

Map-Reading

The work after drill is different for different

11-12

Art of Observation

wings of the school.

The first three weeks, or

For the second week it is as follows:

Jimior Wing, and the last five weeks, or Senior

Monday:

8-9 A. .M

9-10

Study Hour

Art of Observation

Wing, have the following schedules:

10-11

Map-Reading

11-12

Nomenclature

FIB8T THREE WEEKS

LAST FIVE WEEKS

2- 3:50 P.M.

Miniature range

JUNIOR WING

SENIOR WING

Tuesday;

8-9 A. M.

Machine-guns

7- 8 A. M. DrIU

7- 8 A. M. Drill

9-10

Study Hour

8-9 " Class

8- 9 " Class

10-12 "

Gasoline engines

9-10 " DrUl

9-10 " Class

2- 2:50 P.M.

Art of Observation

10-11 " Class

3- 3:50 "

Instruments, including Compasses

11-12 " Calisthenics

11-12 " Class

Wednesday

8- 9 A. M.

Study Hour

12 M. Mess

9-10

Reconnaissance

2- 3 p. M. Drill

2- 3 P. M. Class

10-12 "

Gasoline engines

S- 4 " Calistiienics

3-4 " Class

2- 3:50 P.M.

Miniature range

*- 5 " DriU

4-5 " Calisthenics

Thursday:

8-11 A. M.

Rigging and Landing Gear

5:45 P.M.

First Call

11-12

Study Hour

5:50 "

Retreat

2- 3:50 P.M.

Gasoline engines

5:55 "

Assembly

Friday:

8-9 A. M.

Tools

March to mess

9-10 "

Study Hour

7 :55 p. M.

School Call

10-11

Machine-guns

8:55 "

Dismissed or Recall

11-12

Art of Observation

9:10 "

Tatoo

2- 3:50 P.M.

Gasoline engines

9:15 "

Roll Call in barracks

Saturday:

8-9 A. M.

Study Hour

9:30 «

In bed — and lights out

9-10
10-11

Instruments, including Compasses
Wireless

Every Saturday morning

between 7 and 8 inspection of the

11-12

Reconnaissance

entire student company is

held under arms on the drill field.

and is followed by inspection of barracks by the commandant.

During the third week it is as follows:

Monday:

8-10 A. M.

10-12

Gasoline engines
Machine-gun test

Instruction in the Junior Wing

2- 3 p. M.
3-4

Instruments, including Compasses
Study Hour

Instruction in the Junior Wing consists of

Tuesday:

8- 9 A.M.

9-10

Theory of Wireless
Lecture on Photography

elementary work in

wireless, such as sending

10-11
11-12 "

Machine-guns
Study Hour
Miniature range

and receiving, machine-gun instruction and ma-

2- 3:50 P. M.

chine-gun theory.

Wednesday.

8-9 A.M.

9-10
10-11
11-12

Study Hour

Meteorology

Astronomy

Lecture on Fighting In the Air

Instruction in the Senior Wing

Thursday:

2- 3:50 P.M.

8-9 A. M.

Gas-engines
Study Hour

Instruction for the first week in the Senior Wing is as follows:

9-10
10-11 "

Instruments, including Compasses

Contact patrol

Tools

MOXDAT: 7- 8 A. M.

Drill

11-12

8-10

Wireless

2- 3:50 P. M.

Miniature range

10-12

Gas-engines

Friday:

8- 9 A. SI.

Study Hour

2- 3:50 P. M.

Machine-guns

9-12

Rigging and Landing Gear

TUMBOAX: 8-9 A. M.

Lecture, Type of Machine

2- 3 P. M.

Signal Instruction

9-10 "

Lecture, Bombs and Bombing

3-4

Map-reading

10-11

Lecture, Wireless

Saturday:

8-9 A. M.

Buzzer Practice

11-12

Lecture, Theory of Flight

9-10

Machine-guns

2- 330 P.M.

Lecture, Gasoline Engines

10-12

Bombs and Bombing

Weoxesoay: 8-9 a.m.

Theory of Wireless

9-10

Nomenclature

For the fourth week it is as follows:

10-11

Reconnaissance

Monday:

8-9 A. M.

Study Hour

11-12 «

Map-Reading

9-12

Rigging and Landing Gear

■ 2- SaO P. M.

Gas-engines

2- 3:50 P. M.

Gasoline engines

Thuudat: 8-9 a.m.

Nomenclature

Tuesday:

8-9 A. M.

Study Hour

9-10

Study Hour

9-10

Machine-guns

10-11 «

Bomlis and Bombing

10-12

Miniature range

11-12

Machine-guns

2- 3:50 P.M.

Gasoline engines

2- 2:50 P. M.

Wireless

Wednesday:

8-10 A. M.

Gasoline engines

3- 3:40 "

Theory of Wireless

10-1 1

Meteorology

PUDATi 8-9 A. M.

Study Hour

11-12

Photography

9-10 "

Art of Observation

2-3 P. M.

Radio and Wireless

10-11

Theory of Wireless

3-4

Signal telegraphy

11-12

Machine-guns

TaUlSDATi

8-9 A. M.

Theory of Wireless

9- S'M r. M.

Gasoline engines

9-10

Theory of Sending and Receiving

TRAINING AVIATORS FOR UNITED STATES ARMY

185

Lieutenant Montariol,
French Flying Corps, in-
structing a class of avia-
tion students somewhere
in America.

Thursday:

10-12

A. M.

2- 3

P. M.

3- 4,

Friday :

8-10
10-12

A. M.

2- 4

P. M.

Saturday :

8-10

A. M.

10-12

((

For th

Monday:

8- 9

A. M.

9-12

2- 4

P.M.

Tuesday:

8-11

A. M.

11-13

2- 3:50

P. M.

Wednesday:

8- 9

A. M.

9-10

10-11

11-12

((

2- 3:50

p. jr.

Thursday :

8-10

A. M.

10-12

((

2- 3:50

p. M.

Friday:

Saturday :

8-10

10-12

7- 8

Examination in theory of Sending

and Receiving Wireless
Machine-guns

Instruction in Wigwag and Sema-
phore

Gasoline Engines

Examination in the Theory of
Flight

Machine-guns

Gasoline Engines

Examination in Gunnery, includ-
ing bombs and bombing, and
machine-guns
e fifth week:

Examination in Wigwag and
Semaphore

Work in the field with a field wire-
less set, as used by the United
States Army in the field

Study Hour

Sail-making and Rope-splicing

Study Hour

Examination on the theory of Gas-
oline Engines

Study Hour

Lecture on Magnetos

Signal Telegraphy

Meteorology

Care of machine

Rotary gasoline engines

Miniature range examination

Transportation of machines. Ver-
bal examination on motor-
trucks

Aerial observation, which consists
of fighting in the air, recon-
naissance and map-reading

Engines

Inspection

Training at Army Aviation Schools

Graduates of the Schools of Mihtary Aero-
nautics (ground schools) are assigned through

the Aero-Personnel Division in cooperation
with the O. & T. Section, to the various aviation
school squadrons for instruction in actual fly-
ing. From this point on the flying students
are in charge of the O. & T. Section.

Following is a list of the location of aviation
school squadrons organized and to be organized
in the near future. As time goes on, doubtless
this schedule will be extended.

Mineola, N. Y. — Operating.

Mt. Clemens, Mich. (Selfridge Field).—
Operating.

Fairfield, O. (Wilbur Wright Field) .—Op-
erating.

Rantoul, 111. (Chanute Field). — Operating.

So. Mississippi Valley. — Under investiga-
tion.

San Antonio, Tex. — Operating.

San Diego, Calif.^Now operating.

Belleville, 111. — Operating.

One station to be in Rocky Mountain Re-
gion.

Fort Sill, Okla. (advanced school operating) .

At the above schools training is done with as
much rapidity as possible. At the conclusion
of from fifteen to twenty-five hours' flying, it
is expected students will be able to pass tests
for certificates as Reserve Military Aviators.

While undergoing this flying instruction, the

186

TEXTBOOK OF MILITARY AERONAUTICS

Training America's first thousand aviators. The photo shows three training aeroplanes in the air at one of the training fields.

pupil is required to study radio, gunnery, pho-
tograph}', motors and aeronautical engineering.
This study is practical; the student handles and
operates everj' instrument, assembling and dis-
assembling engines, and does construction and
repair of aeroplanes to the extent that he must
assemble, disassemble, line-up, etc. In the
^nnery instruction, for instance, the student
uses a machine in which a gun is mounted and
is given target practice at objects moving in the
air.

Upon receiving their certificate, these flying
students are commissioned as First Lieuten-
ants, Signal Officers' Reserve Corps, Aviation
Section, and when on duty involving frequent
or continuous flying, receive twenty-five per
■cent, increase in pay. The base pay is $2,000 a
year. When on foreign duty ten per cent, in-
crease on the base pay is allowed. Quarters
are also furnished.

Standard aero-squadrons of the army are
formed at the aviation school squadrons. The
flying and enlisted personnel for these squad-
rons is furnished from these flying schools.
The officers, of course, are Reserve Military
Aviators by this time, though some may be
Junior Military Aviators. The enlisted men

are of the Enlisted Reserve Corps, or of the
Regular Army.

These areo-squadrons, thus formed, will be
fully equipped, save as to aeroplanes, and trans-
ported to England or France for advanced
training.

These graduated aviators (R. M. A.'s) may
also be sent to complete the complement of areo-
squadrons already in process of formation or
partially filled, to be maintained at certain
points.

Tests for an Aviator's Certificate

In different stages of training the student or
mihtary aviator may go through tests and ob-
tain the following certificates:

(1) The F. A. I. Certificate. This is the
international certificate issued under the rules
of the International Aeronautic Federation by
the Aero Club of America. It represents the
federation in the United States and in other
countries on the American continent which do
not have a national areo club affiliated with the
International Aeronautic Federation.

It is necessary to have this certificate to enter
aeronautic meets, and to have records homolo-

TRAINING AVIATORS FOR UNITED STATES ARMY

187

gated and accepted by the International Aero-
nautic Federation.

Following are the rules under which F. A. I.
certificates are granted by the Aero Club of
America :

1. A person desiring a pilot's certificate must
apply in writing to the Secretary of the Aero
Club of America. He must state in his letter
the date and place of his birth, and enclose
therein two unmounted photographs of himself
about 2^/4 X 21/^ inches, together with a fee of
five dollars. In case the applicant is a natural-
ized citizen of the United States he must sub-
mit proof of naturalization.

2. On receipt of an application the Secretary
will forward it promptly to the Contest Com-
mittee, which, in case of an application for an
aviator's certificate, will designate a representa-
tive to supervise the test prescribed by the In-
ternational Aeronautical Federation, and will
advise the representative of the name and loca-
tion of the applicant and, through the Secre-
tary, advise the applicant of the appointment
of the representative to take the test.

3. In case the application is for a spherical
balloon or for a dirigible balloon pilot's certifi-
cate the applicant will be fully advised by the
Contest Committee.

4. All applications for aviator's certificates
must reach the Secretary a reasonable time in

advance of the date that the applicant may ex-
pect to take the required test.

5. No telegraphic applications for certificates
will be considered.

Applicants for each class of certificate must
be of the age of 18 years, and in the case of dir-
igible certificates 21 years, and must pass, to
the satisfaction of the properly designated rep-
resentatives of the Aero Club, the tests pre-
scribed by the F. A. I., as follows:

Spherical Balloon Pilot's Certificate

Candidates must pass the following tests:

(A) Five ascensions without any conditions.

(B) An ascension of one hour's minimum
duration undertaken by the candidate alone.

The issue of a certificate is always optional.

Dirigible Balloon Pilot's Certificate

Candidates must be 21 years of age.

They must hold a spherical balloon pilot's
certificate and furnish proof of having made
twenty (20) flights in a dirigible balloon at
different dates.

They must also undergo a technical examina-
tion.

A group of aviation students at one of
the army training fields.

188

TEXTBOOK OF MILITARY AERONAUTICS

In case, however, the candidate does not al-
ready possess a spherical balloon certificate, he
must have made twenty-five (25) ascensions in
dirigibles before he can apply for a certificate.

The application for the certificate must be
countersigned by two dirigible balloon pilots,
■who have been present at at least three of the
departures and landings of the candidate.

The issue of the certificate is always optional.

Aviator's Certificate

1. Candidates must accomplish the three
following tests, each being a separate flight :

A and B. Two distance flights, consisting
of at least 5 kilometers (16,404 feet) each in a
closed circuit, without touching the ground or
water, the distance to be measured as described
below.

C. One altitude flight, during which a height
of at least 100 meters (328 feet) above the
point of departure must be attained; the de-
scent to be made from that height with the
motor cut off. A barograph must be carried
on the aeroplane in the altitude flight. The
landing must be made in view of the observers,
without restarting the motor.

2. The candidate must be alone in the air-
craft during the three tests.

3. Starting from and landing on the water
is only permitted in one of the tests A and B.

4. The course on which the aviator accom-

plishes tests A and B must be marked out by
two posts or buoys situated not more than 500
meters (547 yards) apart.

5. The turns around the posts or buoys must
be made alternately to the right and to the left,
so that the flight will consist of an uninter-
rupted series of figures of 8.

6. The distance flown shall be reckoned as if
in a straight line between the two posts or
buoys.

7. The landing after the two distance flights
is tests A and B shall be made:

(a) By stopping the motor at or before
the moment of touching the ground
or water;

(6) By bringing the aii-craft to rest not
more than 50 meters (164 feet)
from a point indicated previously
by the candidate.

8. All landings must be made in a normal
manner, and the observers must report any ir-
regularities.

The issuance of the certificate is always op-
tional.

Official observers must be chosen from a hst
drawn up by the governing organization of
each country.

Hydroaeroplane Pilot's Certificate

The tests to be successfully accomplished by
candidates for this certificate are the same as

An instructor enlifthtening future air-
men in the intricacies of coast defense.

TRAINING AVIATORS FOR UNITED STATES ARMY

189

those for an aviator's certificate, except that
starting from and landing on the water is per-
mitted in all of the tests.

United States Army Preliminary
Flying Test

(a) Three sets of figures 8 around pylons
1600 feet apart. In making turns around
pylons, all parts of machine will be kept within
a circle whose radius is 800 feet.

(b) Stop motor at a minimum height of 300
feet and land, causing machine to come to rest
within 150 feet of a previously designated
point.

(d) Glides with motor throttled, changing
direction 90° to right and left.

Note. — (a) and (b) may be executed in one
flight; (c) and (d) in one flight. The same
rules apply in starting from and landing on
water. Special attention will be paid to the
character of landings made.

Report of these tests will be submitted to the
officer in charge of the aviation section, with the
information as to whether or not the school will
complete the training of the aviator through the
reserve military aviator stage.

If the preliminary flying test is passed satis-
factorily and a candidate qualifies in other re-
spects, he will be eligible for further instruction
to qualify as a reserve military aviator.

United States Army Reserve Military
Aviator Test

Reserve Military Aviator Test. The reserve
military aviator test will be as follows :

(1) Climb out of a field 2000 feet square and
attain 500 feet altitude, keeping all parts of ma-
chine inside of square during climb.

(2) Glides at normal angle, with motor

throttled. Spirals to right and left. Change
of direction in gliding.

(3) At 1000 feet cut off motor and land
within 200 feet of a previously designated point.

(4) Land over an assumed obstacle 10 feet
high and come to rest within 1500 feet from
same.

(5) Cross-country triangular flight of 30
miles, passing over two previously designated
points. Minimum altitude 2500 feet.

(6) Straight-away cross-country flight of 30
miles. Landing to be made at designated des-
tination. Both outward and return flight at
minimum altitude of 2500 feet.

(7) Fly for 45 minutes at an altitude of 4000
feet.

Any candidate who successfully passes the
Reserve Military Aviator tests will, on apphca-
tion, be granted the "Expert Aviator" certifi-
cate by the Aero Club of America. An aviator
desiring this certificate must apply in writing to
the Secretary of the Aero Club of America, 297
Madison Avenue, New York City, sending the
report of his R.M.A. tests, certified by the com-
manding officer of the school, by one of the of-
ficers who witnessed the tests, or by one of the
officers of the administrative staff, together with
the sum of $5.

The tests for the R.M.A. certificate are ac-
cepted in place of the club's own tests for the
Expert Certificate. These are as follows :

1. A cross-country flight from a designated
starting point to a point at least 25 miles distant,
and return to the starting point without alight-
ing.

2. A glide, without power, from a height of
2500 feet, coming to rest within 164 feet of a
previously designated point, without the use of
brakes.

3. A figure 8 around two marks 1640 feet
apart. In making turns the aviator must keep
all parts of his apparatus within semicircles of
164 feet radius from each turning mark as a cen-
ter.

Enlisted Aviators

Observer

Junior Military Aviator

Aviation Mechanicians.

All enlisted men except
aviation mechanics and en-
listed aviators.

The uniform insignia of the U. S. Aviation Service.

Military Aviator

CHAPTER XV

REGULATIONS FOR UNIFORMS OF U. S. AERONAUTIC PERSONNEL

Regulations and Specifications for the Uniform of Officer Aviators and Enlisted Men
OF the Aviation Section of the Signal Corps Approved June 22, 1917, by the

Secretary of War

Uniform Specifications

Body, to be double breasted, loose sack coat
of soft russet leather, standard-lined through-
out with kersey; to be easy fitting throughout,
buttoned down the side with five large horn but-
tons.

Collar, standing and falling; standing, to be
closed in front with hook and eye, and to be
about one inch high ; cloth of the collar to be of
the same material as the coat, and not less than
four inches, or more than five inches in width,
an attachable flap of the same material as the
coat, five inches in length and two inches in
width, with buttonhole in each end to close the
front of the collar when worn closed.

Pockets, two large hip pockets covered with
a flap, slightly rounded at the corners, the open-
ing to be horizontal and nine inches across ; one
large breast pocket on the left side with eight-
inch vertical opening at the center line of the
body, the pocket to slope down to the left. All
pockets to be patch.

190

Skirt, to extend one third of the distance from
the point of the hip to the bend of the knee, ac-
cording to the height of the wearer.

Shoulder Looj^s, on each shoulder a loop of
the same material as the coat, let in at the sleeve
head-seam and reaching to the edge of the col-
lar, buttoning up at the upper end with a small
horn button, loops to be about two inches wide
at the lower end, and one inch wide at the collai
end, and cross-stitched throughout the entire
length.

Sleeves, to have flaps with buttons to tighten
sleeve around the wrist, one buttonhole in the
flap, with two buttons on the sleeve for adjust-
ing.

Coats, Aviator, Anti-Sinking

Body, to be single-breasted, sack coat of ga-
berdine with the anti-sinking material quilted
between the outside and the lining, quality and
quantity of the anti-sinking material to be of
the approved standard, to button down the front
with five horn buttons; sleeves not to be quilted.

REGULATIONS FOR UNIFORMS OF U. S. AERONAUTIC PERSONNEL 191

Collar, to be a folding collar with a fold not
more than two inches, the coat to fit snugly
around the neck.

Pockets, two pockets, patch, one on each hip.
Six inches horizontal opening without flaps.

Skirts, quilted skirt to extend one third of
way to knee from the hip, according to the
height of the wearer.

Shoulder Loops, on each shoulder a loop of
same material as the coat, let in at the sleeve
head-seam, and reaching to the edge of the col-
lar, buttoning at the upper end with a small coat
button ; loops to be about two inches wide at the
lower end and one inch wide at the collar end,
and cross-stitched throughout the entire length.

Face Mask, Aviators

To be made of chamois in the proper shape to
conform to the general shape of the head ; skirts
to lay flat on the shoulder and chest, and to be
about six inches long. Eye, nose, and mouth
holes to be cut in the proper place for each in-
dividual wearer.

Flying Suit

To be made of gaberdine of approved quality,
unlined.

Body, a one-piece suit with opening in front
from crotch to neck; fastened together with
seven horn buttons.

Collar, a falling collar with one and one half
inch fall, fitting snugly around the neck.

Shoulder Loops, on each shoulder a loop of
gaberdine let in at the sleeve head-seam, and
reaching to the edge of the collar, buttoning at
the upper end with a small coat button ; loops to
be about two inches wide at the lower end, and
one inch wide at the collar end, and cross-
stitched throughout.

Pockets, to have two breast pockets, one on
the right breast to have an eight-inch horizontal
opening with button flap the height of armpit;
the one on the left side to have a vertical open-
ing nine inches in length without flap, but with
button provided for closing; pocket to be large
and extend in a downward direction toward the
left hip.

Sleeves, sleeves to extend well down on the
hand, and to be furnished with flaps for tighten-
ing around the wrist, flaps to be of the same ma-
terial as the suit, with two buttons for adjusting.

Legs, to extend down to the ankles, fitting
rather loosely, with a flap at the bottom of each
leg for tightening around the ankle; two but-
tons for adjusting to be furnished.

Buttons, all buttons to be of horn, and of suit-
able size for the purposes for which they are to
be used.

Gloves, Aviator, Winter

To be made of buckskin or pliable russet
leather of approved quality, lined with fleece of
unborn lamb.

Hand of glove to be of the mitten type, with
the thumb compartment sufficiently large to
permit of its being withdrawn and placed with
the fingers. There shall be a slit across the in-

Summer flying suit of moleskin cloth, unlined, with winter cap of
soft tan-colored leather.

192

TEXTBOOK OF MILITARY AERONAUTICS

terior of the hand, which will permit the fingers
being extended in the opening, the slit must be
sufficiently overlapped so that ordinarily it will
remain closed.

Cuffs to be of the gauntlet type, made of soft
leather and extending about one half the way
up to the elbow, and to be the same color and
material as the glove proper; the fur in the
glove to extend two inches up the gauntlet from
the wrist joint; a strap to be furnished for tight-
ening the glove around the wrist.

Gloves, Aviator, Summer

To be the regular gauntlet type of soft un-
lined buckskin or russet leather, with soft gaunt-
let extending about one half the way to the
elbow.

Goggles

Transparent part to be made of triplex glass ;
mounting for the glass to extend well away from
the eyes; the part of the goggles nearest to the
face to fit snugly, and conform to the general
shape of the face in order to keep out the wind ;
an adjustable elastic tape to be furnished to
hold the goggles in place.

Amber or clear glass to be used, according to
the desire of those wearing them.

Helmet, Aviators, Summer

To be of the football type, of brown pliable
sole leather, to be shaped to conform to the head
and cover the entire head except the face. Ear
flaps are to be attached for the protection of the
ears, and by having shields to keep out the wind.
The entire helmet is to be lined with felt one
inch thick, and to be fastened under the chin
with an elastic tape and tie string; proper holes
for ventilation will be placed over the entire top
of the helmet.

Helmet, Aviators, Winter

To be of soft russet leather lined with fur;
to he shaped so as to cover the entire head ex-
cept the face; to be fastened under the chin with
a .strap and buckle or patent snap, the front of
the helmet to extend down to the eyebrow.

Aviation Service

Officers of the Aviation Service who are Mil-
itary Aviators shall wear an insignia on the left
breast, the insignia to be embroidered in silver
on blue background, and shall be two wings with
the shield between; the wings shall be three
inches from tip to tip, each wing shall be one
and one eighth inches long, and nine sixteenths
inch wide at the contour ends; the shield shall
be nine sixteenths inch high and five eighths inch
wide, with the letters "U. S." one quarter inch
high in the center below the horizontal cross
lines. See exhibit A.

Junior Military Aviators shall wear on their
left breast the same insignia described for the
Military Aviator, except that the right-hand
wing shall be omitted, the insignia consisting of
one wing to the left of the shield. All officers
in the Aviation service shall wear the Signal
Corps crossed flags on their collar. See Ex-
hibit A.

C'liiiiiKii^ skin iiiii^k iinil Ic.'itlicr coat

REGULATIONS FOR UNIFORMS OF U. S. AERONAUTIC PERSONNEL 198

Mufflers

Mujflers: To be closely- woven wool or cam-
els' hair, O. D. color, sixteen inches wide and
one and one half yards long, the ends to be made
up with a fringe the same as those in common
use.

Shoes, Aviator, Winter

To be of soft russet leather, lined with fleece,
and extending one half way to knee; to have
heavy sole, and made in the boot form or to be
laced up wholly or partially in the front.

Boots, Rubber, Wading (wading pants)

To have regular boot feet, but the legs to ex-
tend up in regular trouser form, the top to be at
a height just under the armpits; adjustable sus-
penders to be furnished for holding the tops up.

Breeches, Winter, Motorcycles

To be made of gaberdine, the same shape and
style as the service breeches as issued. They
will be lined with kersey throughout.

Face Mash, Goggles, Helmet: Same as for
summer.

Hood: To be closely -woven O. D. wool, and
cover the entire head except face; to fit snugly
■and extend well down on shoulders; must cover
forehead down to eyebrows.

Insignia, Sleeve

Enlisted men of the Aviation Section shall
have a navy blue cap let in at the sleeve head-
seam and extending down the sleeve five and one
half inches from the point of the shoulder. All
men as hereinafter specified will wear the in-
signia as described.

A four-bladed propeller with center three
and three fourths inches from point of shoulder,
embroidered in white; the propellers to be two
inches in diameter, two of the blades horizontal
and the other two vertical; three fourths of an
inch above the top tip of the vertical propeller
l)lade a figure showing the number of the squad-
ron to which the man belongs, one inch high,
and embroidered in white. See Exhibit C.

Aviation mechanician, same as above with a
white embroidered circle added, inside of circle
to be one and one fourths inches from center of
the propellers, outside of the circle to be one and
three eighths inches from the center of the pro-
pellers. See Exhibit B.

Enlisted aviator, on the same blue back-
ground shall be embroidered in white, the in-
signia as hereafter described. A pair of wings
with a five-inch spread with crossed propellers
between them, each wing to be one and seven
eighths inches long and seven eighths of an inch
high at the inner edge. Propellers to be one
inch across. One fourth inch above the top tip
of the vertical propeller shall be embroidered
the number of the squadron to which the man
belongs in figures one half an inch high. See
Exhibit C.

Leg gins: All mounted men, and enlisted
men of the Aviation Section, Signal Corps,
canvas with leather reenforcement, as issued.

Muffler: Same as for aviators.

Overalls, Mechanics: To be of standard
denim material, but made in one piece, to open
up in front from crotch to neck, and button up
with seven small buttons, to fit snugly around
the neck, with no collar, each sleeve to be pro-
vided with a flap for tightening around the
wrist; to have two hip and two back pockets,
each pocket to have a six-inch opening, the legs
to extend to the ankles, and to be provided with
flaps for tightening around the ankles.

Changes In Regulations for the Uniforms of

the United States Army, 1914,

to Cover Aviation

Special articles of clothing for aviation pur-
poses are provided and authorized as indicated
hereafter. They are in addition to the usual ar-
ticles of clothing for garrison and field service.

All officers and enlisted men on duty in the
Aviation Section will obtain them on memoran-
dum receipt from the Quartermaster. They
will be held in addition to all the other clothing
as required by these regulations.

Breeches for Motorcycle Messengers: In
cold weather motorcycle messengers in the Avi-
ation Section will wear kersey-lined gaberdine

194

TEXTBOOK OF MILITARY AERONAUTICS

breeches of standard pattern over their service
breeches.

Officers detailed in the Aviation Section and
qualified as Mihtary Aviators will wear the
double or if quahfied as Junior Military Av-
iator the single wing shield over their left
breast.

Officers detailed in the Aviation Section of
the Signal Corps will wear the following insig-
nia to show their qualifications :

Military Aviator: A silver-embroidered
double wing shield on the left breast, above the
line prescribed for badges and medals.

Junior Military Aviator: A single wing sil-
ver-embroidered shield on the left breast, above
the line prescribed for badges and medals.

Rubber Wading Boots (wading pants):
For use of officers and enlisted men on duty with
Hydroaeroplane Squadrons, rubber wading
boots with the top extending up, in the form of
breeches, well beneath the armpits will be fur-
nished. They will be held up by adjustable
suspenders.

Coats, Leather, Aviator (or in case of water
squadron, anti-sinking coats) : Will be worn
while engaged in flying, except in the trop-
ics, where the leather coat may be dispensed
with.

Face Mask: Of chamois, will be worn by of-
ficers and enlisted men flying or enlisted men
riding motorcycles in cold weather.

Flying Suit: A one-piece flying suit of gab-
erdine used by all officers and enlisted men
while flying. It will be worn under the leather
coat.

Winter: They will be worn by chauffeurs
and motorcycle messengers of the Aviation
Section of the Signal Corps during cold
weather.

Aviator: While engaged in flying, aviators
will wear gloves prescribed, fur-lined mittens
with gauntlet tops will be worn in cold weather,
and the plain buckskin or leather gauntlets in
warm weather.

Goggles: Improved type of triplex goggles
will be worn by all aviators and motorcycle mes-
sengers in the Aviation Section of the Signal
Corps while engaged m their respective duties.
Chauffeurs will wear them in the winter. Clear

Brigadier-General B. D. Foulois, wearing the military aviator
insignia.

or amber colored glass, according to the desire
of the person using them.

Blue denim hat will be worn by enlisted men
of the Coast Artillery, Quartermaster Corps,
Aviation Section of the Signal Corps and Field
Companies of the Signal Corps, when on duty
on cable ships, with the fatigue uniform.

Helmets. Aviators and Motorcycle Messen-
gers, will wear special helmets prescribed. In
the summer they shall be of pliable russet
leather, lined with felt ; in the cold weather, avia-
tors will wear a fur-lined soft russet leather
helmet.

On the shoulder loops of the ser\'ice and white
uniforms, and aviators' outside suits or coats,
metal insignia of rank will be worn as fol-
lows:

Enlisted men of the Aviation Service will
wear embroidered insignia on the right sleeve
just below the shoulder as follows:

Enlisted men in the Aviation Section will
wear a white embroidered insignia with crossed
propellers, with the number of their squadron

REGULATIONS FOR UNIFORMS OF U. S. AERONAUTIC PERSONNEL 195

above, on blue background, on the upper, right
sleeve.

Aviation mechanicians will have in addition,
a white, embroidered, circle around the propel-
lers.

Enlisted aviators will wear an insignia with
double wing, crossed propellers with the numer-
ical designation of the squadron embroidered
on the blue background on the upper right
sleeve.

Mufflers: Aviators, motorcycle messengers
and chauffeurs of the Aviation Section will
wear an O. D., closely-woven wool muffler dur-
ing cold weather.

While doing fatigue, enlisted men of the Avi-
ation Section will wear a one piece denim me-
chanic's overalls, as authorized.

Officers, Aviation: A soft russet leather
fleece-lined, high-top shoe with heavy sole will
be worn by officer aviators while flying during
cold weather.

Enlisted men aviators, and motorcycle
messengers will wear high-top russet leather,
heavy-soled shoes, lined with fleece, dur-
ing cold weather, while flying or riding motor-
cycles.

Aviators and Motorcycle Messengers will
wear special, closely-knit, all-wool, coat sweater
during cold weather.

Aviation Officers: In addition to the articles
listed under "a" and "b" for mounted and dis-
mounted officers, officers acting as pilot will se-
cure and have in their possession the following
articles :

1. Aviator's winter helmet.

2. Aviator's summer helmet.

3. Clear or amber, triplex glass goggles.

4. Muffler.

5. One-piece flying suit.

6. Leather coat.

7. Aviator's winter gloves.

8. Aviator's summer gloves.

9. Aviator's winter shoes.

10. Aviator's sweater.

11. Aviator's face mask.

Note: In case of the officer being with a
water squadron, an anti-sinking coat will be sub-
stituted for the leather coat.

UNIFORMS OF THE UNITED STATES
ARMY

Table of Occasions

Officers

Service Uniform and Equipment

Occasions By whom

Articles
E.

minter.

Aviator's winter

helmet.

Face mask.

Goggles.

Muffler.

Flying suit.

Aviator's winter

gloves.

Aviator's shoes.

Sweater.

O. D. Shirt.

1. For all offi-

10.

Service breeches.

cer aviators

Leather Coat.

, ,-, . and observ-
4. For garri- ^^^

^°° ''"ty engaged in

summer.

flying land

Aviator's summer hel-

machines.

met.

Goggles.

One-piece flying

suit.

Leather coat.

Aviator's summer

gloves.

O. D. Shirt.

Service breeches.

Russet leather shoes.

Russet leather leggins.

tropics.

Same as summer

except

omit leather coat.

Note 1. For water machines substitute in winter anti-sinking
coat for leather coat. In summer, substitute anti-
sinking coat for leather coat. In tropics, substitute
anti-sinking coat for flying suit and leather coat.

E.
Add to garrison uniform.

On person

1. Identification tag.

2. First aid packet and

pouch.
For all officer 3. Watch,
aviators a n d 4. Notebook and pencil.
5. For field observers while 5. Compass.
duty engaged in fly-

inff. In machine

1. Haversack containing

meat can, knife and
fork, and spoon.

2. Canteen with cover.

3. Cup.

4. Field Glasses for Observ-

ers only.

Note: — When not flying, aviators and observers will substitute
campaign hat for aviator's head gear.

helmet.

la.

Enlisted Men

Winter

Aviator's winter

Face mask.

Goggles.

For garri-

All enlisted avi- 4.

Muffler.

son duty

ators and ob- 5.

Flying suit.

while en-

servers. 6.

Aviator's winter

gaged in

Aviator's shoes.

flying-

Sweater.

O. D. Shirt.

10.

Service breeches.

11.

Leather coat.

gloves.

196

TEXTBOOK OF MILITARY AERONAUTICS

Occasion*

By whom.

Articles

Summer.

I. Aviator's summer helmet.

J. Goggles.

3. One-piece flying suit.

4. Leather coat.

5. Aviator's summer gloves.

6. O. D. Shirt.

7. Service breeches.

8. Russet leather shoes.

9. Russet leather leggins.

In tropics.

Same as summer.
Omit leather coat.

Ic.

For men tend-
ing.

t'oT garri-
son duty, For Chauffeurs.
.\ VI all on
Section.

Winter.

For garri-
son duty. For mechanl-
Aviation cians.
Section.

Winter cap.
Alasl«an Pea Jacket.
One piece mechanic's

suit.
O. D. Shirt.
Service breeches.
Russet Shoes.
Arctics.
Gloves, woolen.

1.
2.
3.

4.
S.
6.

7.
8.

Summer.

1. Blue Denim hat.

2. One piece suit, me-
chanics.

3. O. D. Shirt.

4. Service breeches.

5. Russet shoes.

Tropics.

Same as summer.

Omit shirt and breeches.

Water Machines.

Add wading pants, and
omit one piece suit.

Winter

1. Winter cap.

2. Goggles.

3. Muffler.

4. Alaskan Pea Jacket.

5. Aviator's winter gloves.

6. O. D. Shirt.

7. One piece mechanic's

suit.

8. Service breeches.

9. Leggins, leather.
10. Russet shoes.

Oceation

lb.

For garri-
son duty.
Aviation
Section.

By who

A rticles

Summer.

Service cap.

One piece mechanic's
suit.

O. D. Shirt.

Service breeches.

Leather leggins.

Russet shoes.

Tropics.

Same as summer, except.

omit O. D. Shirt, and

service breeches.

Winter.

Aviator's winter helmet.

Hood.

Goggles.

Face Masks.

Muffler.

Alaskan Pea Jacket.

Fleece-lined gauntlets.

Kersey-lined breeches.

Aviator's winter shoes.

10.

O. D. Shirt.

11.

Service breeches.

12.

Leather leggins.

For all

motor-

Summer.

cycle

messen-

Aviator's summer hel-

gers.

met.

Goggles.

One piece mechanic's
suit.

Gloves, summer, aviators.

Leather leggins.

O. D. Shirt.

Service breeches.

Russet shoes.

6a.

For Field
Service for
Aviation

Tropical.

Same as summer, except
omit gloves, O. D. Shirt,
and service breeches.

For enlisted
aviators.
For motorcycle

men. ^dd to garrison uniform.

For mechani- 1. Identification tag.
cians.

For Chauf-
feurs.

CHAPTER XVI

AERONAUTIC MAPS

Maps have always been most important fac-
tors in military and naval operations, as they
have been important factors in peaceful travel
over land and water.

A map is as important to the aviator as it is
to the navigator at sea. As the mariner's chart
must tell the navigator of currents, depths of
water, and location of rocks and reefs, so the
aeronautic map must tell the aviator the char-
acter of the land and the configuration of the
bodies of water below him. It must show the
land as it is, the exact shape of cities, woods, and
lakes; the trend of rivers, railroads, and roads;
it must indicate clearly the prominent land-
marks and the established aerodromes and open
fields suitable for landings, etc., etc. In other
words, the aeronautic map must show the con-
tours and configuration of the land as closely as
possible to the way it looks to the aviator from
the air.

Five Types of Aeronautic Maps

There are four types of aeronautic maps used
in the present war, and one type is in prepara-
tion in the United States. The former are as
follows :

(1) The General Aeronautic Map. — This is
based on existing maps, usually on a scale of
1 :200,000, but differs from the average maps in
that the roads are shown in red, the railroads
in black, forests and woods in green, and water-
ways in blue.

(2) The Special Aeronautic Map. — (Illus-
trated herewith.) Besides including every-
thing in the first chart, this shows aerodromes
for aeroplanes and dirigibles, landing fields
where there are no hangars, stations where gas
for dirigibles is obtainable, the approximate
shape of cities, towns, and villages, and such
landmarks as prominent churches, railroad sta-

tions, windmills, smokestacks, castles, and mon-
uments.

These maps are used in long-distance flights
and raids. When a flight is planned the avia-
tors go over the map, lay down the route to be
followed, and study the details given on the
map, together with any other information they
may be able to obtain regarding the configura-
tion of the land over which they will fly, possible
landing places, etc. It is needless to add that
the aviators make every effort to ascertain as
nearly as possible the nature of the enemy coun-
try, in order to recognize the locations where
bombs are to be dropped, as well as where anti-
aircraft guns are most apt to be waiting.

(3) The Special Aeronautic Map for Per-
manent Aerial Routes. — This gives only im-
portant information required by the aviator to
travel over a certain route. This type of map,
which is illustrated herewith, originated in Italy,
and has not yet been put into general use out-
side of Italy. It is a most remarkable map.
The rivers and lakes are shown in blue, in their
exact form. The roads are given in brown, the
railroads in black. The ajiproximate shape of
cities and towns is given in black, and the most
prominent building of each city or town, to be
used as a landmark, is reproduced. The woods
and forests are also shown; and the elevation at
different points is given in meters, so that the
pilot can rise in case he is caught in a fog after
passing a given place, and thus avoid flying into
a hill. In view of the fact that his altimeter or
barograph gives only the altitude above sea-
level, or the altitude from the point of start,
it is necessary for the aviator to know the ap-
proximate elevation of the land below.

The aerial route to be followed, which is
permanent, is marked in red dotted lines. The
aerodromes are shown in red circles; the land-
ing-places which permit landing from two points

197

198

TEXTBOOK OF MILITARY AERONAUTICS

are indicated by two red dots of the same size,
connected with a red line; the landing-places
which permit landing only from one side are
indicated by one red dot, connected by a short
line and a smaller red dot. These dots are most
important, as the large dot represents the ap-
proximate place where the wheel of the aero-
plane must touch on landing. The line that
connects it with the smaller dot shows the direc-
tion toward which the aeroplane must run in
landing. The distance between the first dot
and the second is usually about 300 meters, and
the width is usually about 100 meters. This
type of map greatly facilitates aerial navigation.
(4) The Photographic Map of Sectors. —
Military operations are based on these maps.

This style of map is most important, and is cor-
rected daily, often several times a day, to include
the changes shown by photographs taken by
aviators from their aeroplanes. These photo-
graphic maps show the configuration to the most
minute detail and with the utmost care, as the
success of certain operations depends upon the
exactness of the smallest topographical detail.

Aerial photography is now almost an exact
science. An aviator at a height of from 6000
to 8000 feet can take a photograph which will
include and show clearly all of Manhattan Is-
land; and the photograph can be enlarged to
show the main streets, docks, bridges, and, of
course, the buildings. A series of photographs
could be taken from New York to Albany which

would permit making photographic maps of the
entire route, and show every detail on an exact
scale. This could not be accomplished, even
with the expenditure of years of time and large
sums of money, by any other method. The
expert maker of photographic maps quickly fig-
ures out the scale, and combines photographs to
make a continuous map.

An aviator might fly from Albany to New
York in what is considered a slow aeroplane at
about 70 miles an hour, and take a motion-pic-
ture of the entire route, giving the exact topo-
graphical conditions, thus permitting the mili-
tary authorities within twenty-four hours to
conduct operations with absolute certainty as to
conditions obtaining throughout this region.

(5) The Sj^erry Aeronautic Map. — This

type of map is made on the basic principle of the
"Special Aeronautic Map for Permanent Air
Routes" described above, although it was
evolved entirely independently of the latter, and
has several improvements.

Mr. Lawrence B. Sperry has been working
on these maps and with the cooperation of the
Committee on Aeronautic Maps and Landing
Places of the Aero Club of America, the Aerial
League of America, and the Aeronautic Li-
brary is preparing a map of the Wilson Airway
from New York to San Francisco, which will
make it possible for an aviator to fly across the
continent without the possibility of losing his
way.

Maps of the air-routes between New York
and Chicago, New York and Newport News,

200

TEXTBOOK OF MILITARY AERONAUTICS

Va., and about Long Island, have also been pre-
pared and are ready for the insertion of the
aerodromes now being established by the Army
Air Service and civil organizations, and of
other landmarks.

The plan is to also show on the map the land-
ing-places for twenty-five or fifty miles on either
side of the straight route, and eventually to
give sketches of the shape of cities and towns,
or the more prominent landmarks which strike
the eye of the air-traveler.

The map being prepared of the Wilson Aerial
Highway will cover a straight route from
New York to San Francisco, but there will be
lines leading from the main line to central land-
ing-places, such as Erie, Cleveland, and Detroit.
All the headings are magnetic on these maps,
and the arrows indicate headings in either di-
rection.

The true heading from one city to another is
determined by projecting the line of flight be-
tween these two cities, and then transferring
this line, by means of parallel rulers, to the
nearest compass rose, from which the true head-
ing is obtained. As the difference between the
geographical and magnetic North Pole differs
at various places on the earth's surface, it is
necessary to correct frequently for this differ-
ence, which is known as "variation." In the
vicinity of Chicago the magnetic needle is found
to point to true geographical north, but as the
journey is continued eastwardly, the error will
be noticed to increase to almost 10 degrees west
at New York. As all the headings on this chart
have been laid out "magnetic," or with variation
taken into consideration, the pilot simply steers
his craft on the charted headings. Wherever
the variation is east, it is necessary to subtract
from the true heading, and when it is west, one
must add the necessary number of degrees, in
order to obtain the proper indication.

As soon as regular air-lines are established
to carry passengers and mail, and aircraft start
from a given station at a given time daily, there
will be added to this map the approximate time
at which aircraft will pass certain places, so that
the aviator can navigate the air with even less
trouble than the sailor navigates the sea. In
fact, an aeroplane equipped with the Sperry

automatic pilot could be set to follow the com-
pass direction in trips of a few hundred miles,
and thereafter the pilot would have practically
nothing to do, as the automatic pilot would con-
trol his machine completely. The pilot would
only have to guard against the drift due to side-
winds, which he would do by occasionally glanc-
ing at his map and looking below to see whether
the prominent landmarks checked with the land-
marks shown on his map. Knowing the speed
of his machine, and having the approximate time
required to reach different places, a glance at
the watch would tell him at what point he should
be at that hour, when he could ascertain whether
the landmarks below were similar to those shown
on the map.

The Map with Photographic Reproduction

of Route and Information Regarding

Prevailing Winds

As soon as large aeroplanes with a broad
dash-board are used, it will be possible to make
maps larger, and to include on the ipiargins a
film reproduction of the entire route, or merely
important places. It may also be found advis-
able to print on the margin information regard-
ing prevailing winds to be met at different
altitudes.

It may later be found that films can easily
be taken of the entire route from New York to
San Francisco, and between other control
points. Such a film can be enlarged to have a
width of between 9 and 12 inches, and the water
can be painted blue, the forests and woods
green, the roads brown, the railroads black, the
aerodromes red, etc. This will furnish an exact
map, not only for the aviator, but for other
commercial and scientific purposes, such as de-
veloping railroads and highways, and surveying
for various purposes.

It is quite possible that the entire cost of
making a photograj)hic aeronautic map of the
route between New York and San Francisco
will not be found as high as that of surveying a
few miles to make an average topographic map.

The War Prevented an International Con-
vention on Aeronautic Cartography

The war prevented the assembling of an in-
ternational convention, held under the auspices

AERONAUTIC MAPS

201

of the Aero Club of America, to discuss
and decide on the basic principles for an
aeronautic map of the world to be
adopted by all nations. This convention
was being ai'ranged in the United States
by the Aero Club at the suggestion of
Rear- Admiral Robert E. Peary, Chair-
man of the Committee on Aeronautic
Maps and Landing-Places of the Aero
Club of America. Admiral Peary at-
tended the Tenth International Geo-
graphical Congress, held at Rome in
January, 1913, at which the subject of
aeronautic maps was discussed. The
report of this congress and the principal
address delivered were translated from
Italian by the writer and printed in
"Flying," the organ of the Aero Club of
America, for September and October,
1913.

At this conference no decision was
reached, or action taken, toward adopt-
ing basic principles for the making of
aeronautic maps, because it was agreed by the
delegates, as it had been agreed by the delegates
that attended the congress of the International
Aeronautic Federation at Vienna in June, 1912,
that the first step to be taken should be to agree
on a scale and conventional signs to be adopted
for an aeronautic map of the world. The aero-
nautic map of the world was then to be supple-
mented by aeronautic maps of different coun-
tries, and of parts of different countries, to be
made on the accepted scale with the use of the
same conventional signs.

It was to bring about this international agree-
ment that the Aero Club of America was ar-
ranging to hold an international convention in
the United States, the object being to do for
the world aeronautic map what was done for the
world chart, as proposed by the International
Geographical Congress at Geneva in 1908.
The purpose of this congress was not only to
agree on a scale and conventional signs to be
adopted for the world aeronautic map, but also
to make the necessary arrangements, through
diplomatic channels or otherwise, to facilitate
the execution of those sheets of this map which
overlapped the frontiers of different countries.

A Sperry map-holder and map.

The war prevented the holding of this con-
vention, but the committee on aeronautic maps
and landing-places of the Aero Club of America
continued its work to advance this project.
The members of this committee are as follows:
Rear Admiral Robert E. Peary, Chairman;
Henry Woodhouse, Vice-Chairman; Bion J.
Arnold, Vincent Astor, A. G. Batchelder,
George F. Baker, Jr., Captain Robert A. Bart-
lett, Bernard H. Baruch, August Belmont,
James Gordon Bennett, Cortlandt F. Bishop,
Captain Mark L. Bristol, U. S. N.; Starling
Burgess, Godfrey L. Cabot, President Aero
Club of Xew England; President Manuel Es-
trada Cabrera of Guatemala; ISIajor Joseph E.
Carberry, U. S. A.; Major C. C. Culver, U. S.
A.; Newcomb Carlton; Lieut. Col. Charles De
F. Chandler, U. S. A.; Captain W. I. Cham-
bers, U. S. 'N.; J. Parke Canning, Roy D.
Chapin, Alexander Smith Cochran, Robert J.
Collier, Howard E. Coffin, Chairman Aircraft
Production Board; Roy U. Conger, Glenn H.
Curtiss, Commander Cleveland Davis, U. S. N.;
Lieut. F. Trubee Davison, N. R. F. C; Lieut.
Col. E. A. Deeds, S. O. R. C; Charles de San
Marsano, Charles Dickinson, President Aero

202

TEXTBOOK OF MILITARY AERONAUTICS

MIHt&ICItO MLLA OUCAftA

SpecUI aeronautic map of permanent aerial routes.

Club of Illinois; F. G. Diffin, W. Earl Dodge,
Brig. General Robert K. Evans, U. S. A. ; Rear
Admiral Bradley A. Fiske, U. S. N.; Elbert
H. Gary, John Hays Hammond, Jr.; W. Av-
erill Harriman, Alan R. Hawley, William
Hawley, Henry B. Joy, Frank S. Lahm, Cap-
tain A. B. Lambert, A. S. R. C; Henry Lock-
hart, Jr.; Lieut. Robert A. Lovett, R. N. F. C;
Harold F. MeCormick, Captain J. C. McCoy,
Emerson McMillan, Eugene Meyers, Jr. ; Cap-
tain James E. Miller, S. O. R. C; Lieut. Com-
mander Henry C. Mustin, U. S. N.; George
M. Myers, President Aero Club of Kansas
City; J. D. Park, George W. Perkins, Prof.
Charles L. Poor, Augustus Post, Ralph Pulit-
zer, Col. Samuel Reber, U. S. A.; Ogden Mills
Reid, Thomas F. Ryan, Alberto Santos Du-
mont, Frank A. Seiberling, Hon. William G.
Sharp, Edwin C. Shaw, I^awrence B. Sperry,
Brig. General George O. Squier, Chief Signal
Officer, U. S. A.; James S. Stephens; Lieut.
Commander J. H. Towers, U. S. N.; K. M.
Turner, George W. Turney, Col. Cornelius
Vanderbilt, W. K. Vanderbilt, L. A. Vilas,
Rodman Wanamaker, Monroe Wheeler, Schuy-
ler Skaats Wheeler, Harry Payne Whitney, G.
Douglas Wardrop, Hugh L. Willoughby,
Henry A. Wise Wood, Orville Wright, Wil-
liam Wallace Young, A. Francis Zahm.

Existing Aeronautic Maps Are the Result of
Work by Aero Clubs

The existing aeronautic majjs are the result
of work done by the Aero Clubs of France,
Italy, and United States. The same pioneer
sportsmen and volunteers who were responsible
for developing aeronautics in the different coun-
tries up to the time of the war, were also respon-
sible for the first aeronautic maps.

The writer well remembers how these pio-
neers, now considered as "pioneers and authori-
ties in aeronautics" and given credit for having
had "wonderful foresight" at that time, were
considered visionaries in 1910, as even in 1914f.
Few people were willing to admit that aircraft
would develop within fifty or one hundred years
to such a point that aeronautic maps would be
needed for aerial navigation. These pioneers
nevertheless went on with their work.

AERONAUTIC MAPS

208

In 1910 officials of the Automobile Club of
America and the Aero Club of America com-
bined their efforts to make a topographical map
of Western Long Island for aeronautic pur-
poses.

The Aero Club of France started, in 1911, to
make an aeronautic map of France. This aero-
nautic map was to consist of about 100 sheets,
24 of which have already been issued and are
used extensively by the French and British Fly-
ing Corps. Mr. Charles Lallemand, the well-
known French scientist, is the chairman of the
aeronautic maps committee of the Aero Club
of France. The basic principle on which aero-
nautic maps are now being made by the Aero
Club of France has been revised so as to bring
them up to date and meet military needs.

In Italy the work of making aeronautic maps
has been shared between the aeronautic authori-

ties, the authorities of the Touring Club of
Italy, and the members of the National Com-
mission of Aerial Touring. The Italian pio-
neers in aeronautic toj)ography include Senator
G. Celoria, the chairman of the National Com-
mission on Aerial Touring; Commander Gio-
vanni Roncagli, Royal Italian Navy and secre-
tary general of the Tenth International Geo-
graphical Congress; Mr. C. Usuelli, and other
well-known Italian scientists. The pioneer
work of these organizations has been of great
value to the military authorities of their re-
spective countries during the present war. In
France and Italy the Aero Clubs were practi-
cally the only sources from which the necessary
information covering aeronautic maps could be
obtained, as no attention had been paid to this
subject before the war by the military authori-
ties.

CHAPTER XVII

HISTORY OF UNITED STATES ARMY AERONAUTICS

As related in the chapter on "The Evolution
of the ^lilitary Aeroplane," the United States
Army holds the distinction of being the first
army in the world to acquire an aeroplane.

The order for the first Wright machine was
placed early in 1908, and tests were made at
Fort Myer, Va., in September of that year.
These resulted in an accident on September 17,
in which Orville Wright, the pilot, was severely

which officers of line organizations could serve
on special details. Lieut. Foulois was sent to
San Antonio to teach himself to fly with the
Wright machine.

Owing to the failure of Congress to allow an
appropriation for army aeronautics, the work of
developing this branch of the service practically
ceased in 1910-11, and officers attached to the
Aeronautic Division kept up their practice

injured, and Lieutenant E. Self ridge, the pass- mainlv by attending aviation meets and follow-

enger, was killed. The next tests took place at
Fort Myer in July, 1909. This machine was
accepted by the Government, and Lieutenants
Frank Purdy Lahm and Benjamin D. Foulois
were assigned to receive instruction from the
Wrights.

An aviation camp was established at College
Park, Md., and Captain Charles DeF. Chand-
ler, then disbursing officer of the Signal Corps,
was appointed Officer in Charge of the Aero-
nautic Division. The following officers were
taught to pilot the Wright machine by Wilbur
Wright during October and November, 1909:
Captain Charles DeF. Chandler, Lieutenant F.
P. Lahm, Lieutenant Benjamin D. Foulois,
Lieutenant Frederick E. Humphreys, Lieuten-
ant T. deWitt Milling, Lieutenant H. H. Ai--
nold, and Lieutenant George C. Sweet, the last
being assigned by the Navy Department.

The first dirigible, delivered to the United
States Army by Captain Thomas G. Baldwin,
was first flown at Fort Myer with Lieutenant
Frank P. Lahm of the 7th Cavalry in charge,
and then was sent to Omaha in the autumn of
1909, with I^ieutenants R. S. Bamberger of the
2nd Cavalry, John G. Winter of the 6th Cav-
alr)% and Oliver A. Dickinson of the .5th Infan-
try in charge. These officers and I^ieutenant
Frank P. Lahm were subsequently returned to
duty with their respective regiments, because of
regulations prescribing a time limit during

204

ing the development of civilian aviation.

During the jNIexican outbreak in February
and JNIarch, 1911, the United States Army had
no aeroplanes to send to the Mexican border.
It was enabled to put an air scout at the dis-
posal of the Government through the courtesy
of ^Ir. Robert J. Collier, the president of the
Aero Club of America, who loaned the army his
Wright aeroplane. With this machine Lieu-
tenant B. D. Foulois and Mr. P. O. Parmalee,
made a number of flights along the Mexican
border, reconnoitering and carrying messages
from General Carter to jSIajor George O.
Squier.

During the winter of 1911 I^ieutenant Paul
W. Beck, G. E. :M. Kelley, and John C. Walker
were assigned to take a course of training at the
Curtiss Aviation School at San Diego, Cal.
They were assigned to duty at San Antonio,
Texas, in April, 1911, to fly the Curtiss ma-
chines acquired by the United States Army.

The first army officer to be granted an F. A.
I. pilot's certificate was Lieutenant F. P. Labni.
Lieutenants II. H. Arnold and T. deWitt Mil-
ling, Captain Charles DeF. Chandler, Lieuten-
ant Benjamin D. Foulois, Captain Paul W.
Beck, Lieutenant R. Carrington Kirtland.
Lieutenant J. W. McClaskey, Ijieutenant Wil-
liam C. Sherman, Lieutenant Harry Graiiam,
and Captain Frederick B. Hennessey, were the

HISTORY OF UNITED STATES ARMY AERONAUTICS

205

next ten army officers to obtain a pilot's certifi-
cate.

By the Act of Congress of March 3, 1911,
there was made available the sum of $125,000
for army aeronautics. This appropriation
made it possible to establish a substantial avia-
tion camp at College Park, Md. This was
moved to Augusta, Ga., during the four winter
months of 1912-13.

Seven aeroplanes were bought for the United
States Army in 1911. Three were Wrights,
three were Curtiss machines, and one was a Bur-
gess biplane. Important experiments were
conducted at College Park during 1911-12, in-
cluding the testing of the Lewis gun and the
Scott bomb-dropping device; also experiments
in sending wireless messages from an aeroplane,
map-making, and other pioneer work.

Early in 1912 steps were taken to form an
aviation section in the Philippines, and one aero-
plane in charge of Lieutenant Frank P. Lahm
was sent to the islands for that purpose.

Lack of funds and shortage of personnel pre-

•■^SOfSW^J^^R?

The Baldwin dirigible, first and only dirigible acquired by the

United States Army up to 1917, being put through

the tests, August, 1908.

Col. (now Gen.) Squier was the Chairman of the Joint Army
and Navy Committee ordered to conduct the tests of the first
Army aeroplane in 1908. The above photograph shows the aero-
plane in the air at Fort Meyer, Va., on September 12th, 1908,
when Orville Wright and Col. Squier, who was the first passen-
ger, made a flight of 9 minutes six seconds, which was a record
for many months.

vented expansion of the air service and exten-
sion of the work of the existing organization.

The Act of August 24, 1912, appropriated
$100,000 for the purchase, maintenance, oper-
ation, and repair of aircraft. Twelve aero-
planes were bought in that year. Major Sam-
uel Reber was put in charge of the Aeronautic
Division.

The exact number of machines and aviators
and the distribution of the United States Army
Aviation Squadron in June, 1913, was as fol-
lows:

Machines
OflScers Training High-powered

Texas City, Texas 11 6 4

San Diego, Cal 5 1 1

Philippine Islands 1 1 1

Four officers were on temporary duty learn-
ing to fly, and Fort Leavenworth, Kansas, had
one high-powered machine.

206

TEXTBOOK OF MILITARY AERONAUTICS

This photograph, which was taken by James H. Hare, at the Mexican border in 1911, shows Col. (now Gen.) Squier on the left

after receiving a message carried by Captain (now Brig.-Gen.) Benjamin D. Foulois and Philip O. Parmalee.

The aeroplane was loaned to the Army by Mr. Robert J. Collier, then president of the Aero Club of America.

The general equipment of this handful of avi-
ators consisted of the barest necessities. The
allowances made by Congress in 1911 and 1912
were too meager to afford more than the neces-
sar\' aeroplanes, tents, and spare parts, while the
1913 allowance of $12.5,000 was bartely sufficient
to replace the wornout machines and afford
maintenance. It was not possible, therefore, to
acquire motor-truck repair-shops, motor-trail-
ers, extra motors, and such other equipment as
was absolutely necessary to create an efficient
organization.

Lacking funds, the Signal Corps was unable
to replace the army dirigible, or to extend the
aerostatic section. Therefore work in that
branch of the service practically ceased.

Aeroplanes were first u.sed in military ma-
noeuvers in August, 1912. Two machines were
assigned to these manoeuvers, in charge of I.,ieu-
tenants B. D. Foulois and Harold Geiger, Cap-
tain F. B. Hennessey, lieutenant T. deW. Mil-
ling, and Lieutenant Harry Graham.

A plan to give the army 120 aeroplanes and to
establish a number of aviation centers was pro-
posed by the Secretary of War in a special re-
port to Congress in response to Resolution 444,
House of Representatives, March 26, 1912,
(House Document No. 718, 62d Congress,
2d Session), but Congress took no action on
it.

The Act of March 2, 1913, allowed a detail
not to exceed thirty officers of the line of the
army to aviation duty, and gave extra pay to
officers engaged in flying.

The Act approved July 18th, 1914, author-
ized an increase of the Signal Corps by the addi-
tion of an Aviation Section. Previous to the
passage of this Act there was no definite provi-
sion of law covering the duties of the Signal
Corps with respect to aviation. Under this Act
the Aviation Section was authorized to have
sixty officers and 250 enlisted men. But the
shortage of officers in every branch of the
service prevented getting more than half that

HISTORY OF UNITED STATES ARMY AERONAUTICS

207

number of officers for the aviation section.

In 1912 twelve aeroplanes were bought, and
in 1913 eight more were added. In 1914 eleven
machines were bought, and in 1915 twenty more
were secured.

The following table gives a list of aeroplanes
purchased by the Signal Corps between 1908
and 1916, with their disposition:

Aeroplanes of All Types Purchased by the
Signal Corps

Date.

Year

1908

19U

1912

Maker. Disposition. Date. Total.

Original Wrightin Smith.sonian Institution 1

Curtiss Condemned February, 1914

Wriglit do do

Do Destroyed by accident. . .September, 1912

Burgess Condemned February, 1914

Curtiss do do

Wright Destroyed by accident .. .August, 1913..

Curtiss Condemned June, 1914. . . .

Burgess do do

Wriglit Destroyed by accident. . .February, 1914

Do do July, 1913 ....

Do do November, 1913

Do do October, 1913. .

Do do November, 1913

Curtiss do April, 1913 ....

Wright do June, 1914 ....

Burgess do January, 1915.

Do do September, 1913

Wright Condemned June, 1914....

Do do do

1913 Curtiss do do

Do do October, 1914 . .

Do do June, 1914....

Burgess do April, 1915. . . .

Do do January, 1915.

Do Out of repair August, 1915..

1914

Year. Maker. DLsposltion.

Burgess-Dunne . In commission

Wright Condemned June, 1915. . . .

Burgess Out of repair

Do Condemned August, 1916. .

Curtiss do January, 1915.

Do do November, 1915

Martin In commission

Do Condemned June, 1915. . . .

Do do do ......

Curtiss In commission

Do do

Martin do

Do do

Burgess Out of repair

Curtiss In commission

Do do

Do Condemned October, 1915. .

Do flo August, 1915 . .

Do In commission

Do do

Total.

1915

Martin do

Do do

Curtiss do

Do do

Martin do

Do Undergoing tests

Do In commission .

Do do

Total

SUMMARY

In Smithsonian Institution

Destroyed and condemned

Out of repair

Now in service, distributed as follows :
Manila —

Hydroplanes 4

San Diego —

Flying boats 2

Training machines 9

Mexican expedition

1
32
3

— 23

Total

View of the Signal Corps Aviation Field, College Park, Md., 1912, taken from an Army machine. (From "Flying.")

208

TEXTBOOK OF MILITARY AERONAUTICS

The first tests of the
now famous Lewis gun
were made by United
States Aviators. Cap-
tain Charles de F. Chan-
dler and Lieutenant T.
De Witt Milling at Col-
lege Park, Md., June 7th-
Sth, 1912.

The Mexican Campaign Found the United
States Army Unprepared Aeronautically

Our utter aeronautic unpreparedness was
shown in ^larch, 1916, when Villa raided Co-
lumbus, Xew JNIexico, and other American lo-
calities along the Mexican Border, killing
Americans and destroying property. Villa
raided Columbus on March 9, and on ^larch 11,
Secretary of War Baker ordered General Scott,
Chief of Staff, to instruct General Funston to
use, as far as possible, the Aero-Squadron sta-
tioned at Fort Sam Houston, San Antonio,
Texas, in his expedition against Villa. General
Funston realized that an aeroplane was easilj'
worth 5000 men in the Mexican campaign, and
that scouts, other than aerial, faced death in
crossing the Mexican Border. As General
Funston pointed out: "Villa parties will at
times surprise these scouting parties. In ordi-
nary warfare our men might, if hopelessly out-
nunil)ered and resistance were futile, surrender
with safety. To surrender to Villa, however,
would be worse than suicide. Villa's men will
kill every American they can lay their hands
pn. Every encounter with them means a fight
to the death for our men."

The aero-squadron at Fort Sam Houston in-
cluded Captain Benjamin D. Foulois, Captain

T. S. Dodd, Lieutenant J. E. Carberry, Lieu-
tenant T. S. Bowen, Lieutenant Ira D. Rader,
Lieutenant C. C. Chapman, Lieutenant H. A.
Dargue, Lieutenant Edgar S. Gorrell, Lieuten-
ant W. G. Kilner, and Lieutenant R. H. Willis.
These aviators joined General Pershing at
Casas Grandes, JSIexico, about 110 miles from
the border.

The squadron had only eight small, low-pow-
ered scout-aeroplanes, not suitable for flights of
over 50 miles from their own base and certainly
not adapted for the difficult conditions under
which the aviators had to fly. It also lacked
general equipment required to keep an aero-
squadron in the field. On IMarch 27, Secretary
Baker made known tliat there were only two
aeroplanes in commission for use by the Mexi-
can Expedition, and that General Funston had
asked for more. In his statement Secretary
Baker said: "The wireless coninnuiication is
reported to be intermittent, because of the static
conditions in the electric field there. For this
reason additional importance is given to the re-
quest for aeroplane facilities."

Congress was asked for an emergency ap-
propriation of $500,000 for aeroplanes. Tliis
sum was provided on March 28, wlicii the Army
Deficiency Bill passed the House by a vote of
878 to 1.

HISTORY OF UNITED STATES ARMY AERONAUTICS

209

Lieutenant Colonel George O. Squier, who
had been military attache at the United States
Embassy at London, was appointed to take
charge of the Aeronautic Division of the United
States Army.

Meanwhile the two available aeroplanes were
kept in daily service carrying despatches and
reconnoitering between General Pershing's
camp at the front and Columbus, N. M. On
April 22 a despatch stated that they were out of
commission, being repaired at Columbus, and
the expeditionary force in Mexico was without
air scouts.

It was soon evident that the $.500,000 emer-
gency appropriation would only meet a frac-
tion of the needs, and that the appropriation of
$1,222,000 asked for aeronautics for the next
fiscal year would be too small to permit start-
ing a substantial air service. The Aero Club of
America then undertook not only to arouse the
country to the need of a substantial air service,
but also to create a reserve of trained aviators.

For several years previously the Aero Club of
America had been urging the expansion of the
army air service, and while it had succeeded in
creating what little interest there was in the
subject, it was far from achieving its aims.
These aims were: "To give the United States
5000 aviators, placing this country in the posi-

tion of the porcupine, which goes about its daily
peaceful pursuits, harms no one, but is ever
ready to defend itself."

Finding it impossible to get authorization for
assigning even 500 army officers to aviation, the
Aero Club turned to forming a reserve of Na-
tional Guard officers from different states. Pa-
triotic citizens contributed to carrying out this
plan.

Mrs. William H. Bliss contributed through
the club the funds necessary to purchase an aero-
plane and train officers of the National Guard
of New York, starting an aero company at
Mineola, Long Island. Lieutenant Raynal C.
Boiling was commanding officer of this com-
pany, which some months later gave the country
a score of good aviation reserve officers.

Messrs. Emerson McMillin, T. Jefferson
Coolidge, Barend Van Gerbig, and others, made
substantial contributions, and the Curtiss Com-
pany offered to train an officer from the Na-
tional Guard of each state.

When Villa raided Columbus the Aero Club
offered to present a number of aeroplanes to the
United States Army and to supply a number of
volunteer aviators. This offer was declined.
But when the two aeroplanes in Mexico went
out of service and the Carrizal tragedy took
place, a request was sent to the club by the sig-

The Hangars at the U. S. Army Aviation School at College Park, Md., 1911.

210

TEXTBOOK OF MILITARY AERONAUTICS

_!<! "fijy.

Four of the aeroplanes of the First Aero Squadron at Columbus, New Mexico.

nal officer for volunteers, and an officer was as-
signed to work with the club in mobilizing civil-
ian aeronautic resources.

The list of volunteers submitted by the club
included about fifty civilian aviators and the
following National Guard officers. The latter
were assigned by their respective Adjutant-
Generals, whose names also follow :

Arkansas. — Brigadier-General Lloyd Eng-
land, the Adjutant-General, detailed Second
Lieutenant Forrest Ward to report at the Cur-
tiss Aviation School, Newport News, Va., for
training.

Colorado. — Brigadier General John Chase,
the Adjutant-General, detailed Lieutenant
Cummings, Signal Corps, National Guard of
Colorado, to report to the Curtiss Aviation
School, Newport News, Va., for training.

Connecticut. — Brigadier General George INI.
Cole, the Adjutant-General, detailed Captain
Ralph L. Taylor, of the Connecticut Coast Ar-
tillery of Stamford, Conn., to report to the Cur-
tiss Aviation School, Newport News, Va., for
training.

Georgia. — Brigadier General Van Holt
Nash, the Adjutant-General, detailed Sergeant
L. V. Smith to report at the Curtiss Aviation
School, Newport News, Va., for training.

Kentucky. — Brigadier General II. Tandy
Ellis, the Adjutant-General, detailed Lieu-
tenant B. Osborn, of the Signal Corps, to report
at the Curtiss Aviation School, Newport News,
Va., for training.

Minnesota. — Brigadier General Fred W.
Wood, the Adjutant-General, detailed Geo. M.
Palmer to report at the Curtiss Aviation School,
Newport News, Va., for training.

Nehra.ika.~Br\frad\er General P. L. Hall,
the Adjutant-General, detailed Captain Ralph
E. McMillin, a licensed pilot, to report at the
Curtiss Aviation School, Newport News, Va.,
to qualify for the "Superior" or "Expert" Li-
cense issued by the Aero Club of America.
This was in response to the Aero Club of Amer-
ica's telegrams sent out March 12. The cost of
obtaining tliis license was borne by the National
Aeroplane Fund.

Netc York.— The Aviation Company of the
National Guard of New York, which had been
training at the Mineola Aviation Field com-
prised the following gentlemen:

Captain Raynal C. Boiling; Lieutenant N.
Carolin; J. E. Miller; A. B. Thaw, 2d Master
Signal Electrician; R. J. Gilmore; First-Class
Sergeants P. R. Stockton, F. R. Dick; Quar-
termaster Sergeant W. T. Odell; Sergeants J.
H. Stevenson and E. A. Kruss; Corporals D.
G. Frost, D. R. Noyes, K. B. Hagerty, W. P.
Willetts, J. R. Speyers, H. H. Salmon, .Ir., P.
J. Roosevelt, F. .1. Hoppin; Privates E. C.
Best, F. Boger, Jr., K. J. Bevens, W. W. Con-
ant, Jr., A. M. Craig, J. T. Dwyer, A. L.
Favre. C. C. Goodrich, P. J. Heiiry, W. T.
Howell, J. F. Hubbard, W. C. Jenkins, W. J.
Johnson, R. .1. Knowlson, E. McCormick, E.
Martin. I). P. Morse, R. M. Olyphant. Jr.. C.
H. Reynolds. R. F. Russell, P. I). Smith, J. D.
Sullivan, T. F Ward, and Trumpeter W. L.
Rockwell.

Buffalo, N. v. — Two members of the Buffalo
Aero Squadron reported at the Curtiss Aviation
.School, Newport News, Va., to receive the same
course of training given the militia officers of the
various states, detailed for instruction by the Ad-

HISTORY OF UNITED STATES ARMY AERONAUTICS

211

jutant-Generals of their respective states.
These two men were: Messrs. Willis G. Hick-
man and Morgan More.

Lieutenant Edward Bagnell was detailed to
accompany Captain McMillin to Newport News
for training.

New Hampshire, — Brigadier General C. W.
Howard, the Adjutant-General, detailed Lieu-
tenant Ai'thur J. Coyle, of the 1st Infantry, to
report at the Curtiss Aviation School, Newport
News, Va., for training.

North Carolina. — Brigadier General L. W.
Young, the Adjutant-General, detailed liieu-
tenant D. B. Byrd, of Company F, 2nd In-
fantry, to report at the Curtiss Aviation School,
Newport News, Va., for training.

Ohio. — Brigadier General W. B. Hough, the
Adjutant General, detailed Lieutenant R. H.
Hoyer, to report at the Curtiss Aviation School
at Newport News, Va., for training.

Oklahoma. — Brigadier General F. M. Can-
ton, the Adjutant-General, detailed Sergeant
Harrison Handley, of the Infantry, to report at
the Curtiss Aviation School, Newport News,
Va., for training.

Oregon. — Brigadier General Geo. H. White,
the Adjutant-General, detailed Captain Frank
W. Wright to report to the Curtiss Aviation
School at San Diego, California, for training.

Chief Mechanic Bairn, an experienced avi-
ator, was detailed to accompany Captain
Wright to San Diego to qualify for the "Su-
perior," or "Expert," License issued by the
Aero Club of America.

Tennessee. — Brigadier General C. B. Rogan,
the Adjutant-General, detailed Lieutenant
Curry A. McDaniels, of the Infantry, to report
at the Curtiss Aviation School, Newport News,
Va., for training.

Texas. — Brigadier General H. Hutchings,

Mustering into the Federal Service the First Aero Company, X. Y. X. G., at Mineola, which was started tliicJUL'li tlic icmtrihu-
tion of Mrs. William H. Bliss and trained at private expense, dose to $60,000 contributed largely through the Aero Club of
America. Most of these men became members of the Signal Officers Reserve Corps. The personnel of the Aero Company, which
includes many members of prominent New York families, as mustered in, was as follows: Captain Raynal C. Boiling, Lieutenant
N. Carolin, J. E. Miller, A. B. Thaw, 3nd Master Signal Electrician; R. J. Gilmore; First-CIass Sergeants, P. R. Stockton, F. R.
Dick; Quartermaster Sergeant, W. T. Odell; Sergeants, J. H. Stevenson, E. A. Kruss; Corporals, D. G. Frost, D. R. Noyes,
E. B. Hagerty, W. P. Willets, J. R. Speyers, H. H. Salmon, Jr., P. J. Roosevelt, F. J. Hoppin; Privates, E. C. Best, F. Boger, Jr.,
K. J. Bevens,"w. W. Conant, Jr., A. M. Craig, J. T. Dwyer, A. L. Favre, C. C. Goodrich, P. J. Henry, W. T. Howell, J. F. Hubbard,
W. C. Jenkins, W. J. Johnson, R. J. Knowlson, E. McCormick, E. Martin, D. P. Morse, R. M. Olyphant, Jr., C. H. Reynolds,
R. F. Russell, P. D. Smith, J. D. Sullivan, T. F. Ward, and Trumpeter, W. L. Rockwell.

212

TEXTBOOK OF MILITARY AEROXAUTICS

i?*-

A squadron of American training uiacliincs at one of the Army Aviation Schools in 191G.

the Adjutant-General, detailed Lieutenant
Byron McMuUen to report at the Curtiss Avia-
tion School, Xewport News, Va., for training.

Vermont. — Brigadier General Lee S. Tillot-
ton, the Adjutant-General, detailed Lieutenant
Harold P. Sheldon, of the 1st Infantry, to re-
port at the Curtiss Aviation School, Newport
News, Va., for training.

Virginia. — Brigadier General W. W. Sales,
the Adjutant-General, detailed Corporal
Greenhow Johnston, of the Signal Corps, Vir-
ginia National Guard, to report at the Curtiss
Aviation School, Newport News, Va., for train-
ing.

West Virginia. — Brigadier General John C.
Bond, the Adjutant-General, detailed Lieu-
tenant Howard F. Wehrle, to report at the Cur-
tiss Aviation School, Newport News, Va., for
training.

As the United States Army had no authoriza-
tion to enroll civilians in an aerial reserve corps,
the latter applied to the Aero Club of Amer-
ica. Applications were received at the rate of
one thousand per month. The club urged Con-
gress to provide for an aerial reserve, and on

May 25, 1916, Mr. Alan R. Hawley, the presi-
dent of the club, flew from New York to Wash-
ington with Victor Carlstrom, carrying a special
edition of the "New York World" containing
indorsements from governors and other state
authorities of the plan to train 2000 aviators.
As soon as the National Defense Act of June 3,
1916, was passed, — an act which provided for
the enrolling of officers and men in the Officers'
and Enlisted Men's Reserve Corps, — a commit-
tee of the club, consisting of jNIessrs. Alan R.
Hawley, Congressman Murray Hulbei't, Ralph
Pulitzer, Robert J. Collier, and the writer,
waited on President Wilson and urged him to
authorize the organization of the Aerial Reserve
Corps.

On July 13, 1916, a telegram from the White
House advised the club that the President had
authorized the organization of the Aerial Re-
serve Corps.

In the meantime a most energetic campaign
of public education was conducted by the club
to bring about an increase of the aeronautical
appropriation from $1,222,000, as estimated, to
$29,000,000, the sum urged by the club. An

Some of the arroplanes In uhp nt the Army Avliitlon Field at Sun Oiego In 1916.

HISTORY OF UNITED STATES ARMY AERONAUTICS

218

The International Aircraft Standardization Committee, which met in Washington, August 14—15, for the first time. Seated,
left to right, F. G. Diffin, U. S., Chairman; G. I.. Xorris, U. S.; Lieut. M. Mignot, France; Capt. J. Herck, France; A. B. Rogers,
England, and S. G. Payne, England. Standing, P. D. Merica, Bureau of Standards; F. G. Ericson, Canada; W. F. Prentice, Eng-
land; Capt. A. Pomilio, Italy; J. S. MacGregor, U. S.; H. Chase and Dr. G. K. Burgess, both of the U. S. Bureau of Standards.

amendment, proposed by Congressman Murray
Hulbert when it first came before the House, to
increase the appropriation to $14,000,000, was
defeated on a point of order. An amendment
proposed by Congressman James Mann, was
adopted, however. This amendment increased
the appropriation to $3,500,000. Senator
George E. Chamberlain, the chairman of the
Committee on Mihtary Affairs, next introduced
the amendment in the Senate, and while it met
with difficulties, it finally was adopted, the ap-
propriation allowed being $13,861,000.

This appropriation permitted the Signal
Corps to develop the aeronautic division on a
more substantial basis, and gave this country a
year's start toward improved aerial develop-
ments.

The Chief Signal Officer, in his report dated
October 3, 1916, has stated that there were
thirty-nine officers detailed in, and forty-six stu-
dents attached to, the Aviation Section.

An official report issued October 20 stated
that the Aviation Section, "ordered 175 aero-
planes for the Army and soon will order 100
hydroaeroplanes and 100 training school ma-
chines to be used in training the Army and the
National Guard." The report also announced
that orders had been signed on that date for the
formation at San Diego of the Second and
Third Aero Squadrons for the Army,

The Report stated further that "the Army
has 45 junior military aviators, with a tactical
staff of six officers, has 38 officers under instruc-
tion at San Diego, where they have been turned
out at the rate of eight a month.

"Major Charles de F. Chandler of the Signal
Corps, who has had practical experience in bal-
looning, has been placed in charge of all military
balloon work, and bids have been advertised for
four army balloons, two spherical and two kite.
The balloon section may be established at
Omaha or at Akron.

"The Army will train officers in flying at San
Diego, where it has eleven training machines
which are to be increased by eighteen hydroaero-
planes. There are six machines at the Mineola
training school on Long Island, and twelve un-
der order for use there. There are four ma-
chines at the Chicago training station and
twelve ordered. The army bill appropriated
$300,000 for purchase of land in California for
aviation school purposes and $300,000 for an-
other large tract. A special board is now consid-
ering the selection of the second site in the East.

"The army has only one thoroughly equipped
areo squadron. It is at Columbus, N. M., and
has twelve 160-horse-power reconnoissance type
of Curtiss aeroplanes, one Curtiss twin-tractor
of 200 horse-power. The army also has one
aero company stationed in the Philippines for

214

TEXTBOOK OF MILITARY AERONAUTICS

coast defense work. It will be raised to aero
squadron strength."

General Orders Xo. 55 provided that the Re-
serve OjBicers of the Aviation Section of the Sig-
nal Corps should consist of 296 officers. An
order issued September 8, 1916, limited the
number of National Guard Officers to be trained
in aviation at army schools to fifty.

On October 11, 1916, President Wilson au-
thorized the creation of the Council of National
Defense and appointed seven civihan members
of the Advisory Committee of the Council, as
follows : Daniel Willard ; Samuel Gompers ; Dr.
Franklin H. Martin; Howard E. Coffin; Ber-
nard Baruch; Dr. HoUis Godfrey; Julius Ro-
senwald.

On February 7, 1917, when it became known
that the House Committee on Military Affairs
in reporting the appropriation for Army aero-
nautics for the ensuing year had allowed only
$8,000,000 for equipment and $1,000,000 for
aeronautic stations, the Aero Club of America

started another campaign of public education
to get the appropriation inci'eased to a minimum
of $50,000,000 and to insure the training of
2000 aviators during 1917.

After a meeting of the National Advisory
Committee on Aeronautics held March 20-31 an
official statement was issued outlining the plans
of the Ai-my and Navy regarding the number of
aviators to be trained and machines to be or-
dered, which read in part as follows :

"There are many estimates of our reasonable
needs, and the one herewitli presented has been
prepared after conferences with as many men as
could be reached who have experience or judg-
ment quahfying them to express an opinion, and
after obtaining as many data as possible from
Europe.

"Tentative estmiate of annual requirements
of aeroplanes ( assumed to be possible of accom-
plishment in 1916) :

"Attached to an army of 1,000,000 men, 1,000
planes and 1,000 aviators.

Thl« photo^aph shows the First Aircraft Production Board in its mcetinff room in the Munsey Huildinp, Wnshintrton, I). C.
Prom left to rl(fht: A. G. Cahle, Secretary of the Board; R. L. Montgomery, .Sidney I). Waldon, K. A. Heeds. Hear Admiral
David W. Taylor, Chief of the Bureau of Construction and Repair, U. S. N.; Brigadier-General George O. Squler, Chief Signal
Oflcer, U. S. A.| Howard E. Coffin, Chairman of the Board.

HISTORY OF UNITED STATES ARMY AERONAUTICS

215

Officers at the Mineola aviation station. From left to ripht, sitting: Capt. li. L. Taylor, oliircr in eliarge ul' flying; l.L. Cliurlcs
Reed, first aero reserve squadron; Capt. P. A. Carroll, first aero reserve squadron; Capt. Frank T. Coffyn, S. O. R. C. ; Maj.
W. G. Kilner, C. O., S. C. A. S., Mineola; Capt. S. W. Fitzgerald, Commanding officer; Capt. Henry, Adjutant, S. C. A. S., Mine-
ola. From left to right, standing: Lt. Stroman, photographic department; I,t. Jones, training department; I,t. L. C. Ricker, quar-
termaster; Lt. W. P. Willetts, technical department; Lt. Olyphant, fir.st aero reserve squadron; Lt. B. O. Watkins, supply depart-
ment; Lt. D. R. Wheeler, supply officer; Lt. H. H. Simons, training department; Lt. Montarial, instructor detailed from French
F. C; Lt. Page, technical department.

"Attached to our fleet at sea, 200 planes and
200 aviators.

"For harbor and seaport defense, 800 planes
and 800 aviators.

"Total, 2,000 planes and 2,000 aviators.

"For training pilots (worn out or broken),
2,000 planes and 400 aviators.

"Total, 4,000 planes and 2,400 aviators."

Seven weeks after the United States' entry in
the war, on May 21, 1917, there was created the
Aircraft Production Board, in the Council of
National Defense, the personnel of which was
as follows: Howard E. Coffin, Chairman;
Brig. Gen. George O. Squier, Chief Signal
Officer, U. S. A.; Rear Admiral David M.
Taylor, of the navy; S. D. Waldon; E. E.
Deeds; and R. L. Montgomery.

The preliminary announcement of the Air-
craft Production Board was as follows :

"We now believe America has started on the
right road toward working out her destiny in the
air and taking the place to which her capacity
•entitles her and which the world expects of her.
We have been in constant touch for weeks with

the aircraft manufacturers on the problem of
the quantity production of machines, and the
Government authorities are already signing
contracts for as many machines as our present
appropriation permits. The United States can
depend on a minimum of 3500 aircraft of all
types for the first year, if Congress authorizes
us to proceed. The program we now have in
mind would provide for both training and com-
bat machines.

"The country has made progress in develop-
ing aviators. Last month a group of army offi-
cers visited the training camp of the Royal Fly-
ing Corps at Borden, Ontario, one of the four
camps established in Canada and the aviation
school at Toronto, where cadets are trained un-
der militaiy discipline for the service. In these
schools there has been incorporated the latest
European experience in the development of this
new art of the air.

"Our officers were deeply impressed with their
observations, and as a result we called together
here the heads of six prominent engineering
schools which also have military training, and

216

TEXTBOOK OF MILITARY AERONAUTICS

made plans to estahlisli u similar system in the
United States. The six institutions are the
Universities of California, Texas, Illinois, Ohio,
JMassachusetts Institute of Technology, and
Cornell University. Three technical instruct-
ors from each of these places were sent to
Toronto. They returned on May 8 after a
comprehensive study of the course given there,
prepared to teach it themselves. On May 10
these six engineering schools opened similar
cadet aviation schools at their respective insti-
tutions. At the end of two months of this pre-
liminary work, the cadet is given a final test to
determine whether he shall go on to the aviation
camp.

"The manufacturing capacity can easily he
doubled the second year. A prominent Brit-
ish General has asserted that America's great-
est contribution to the war will be aircraft and
aviators. We believe that once started upon
quantity production, American mechanical gen-
ius will overcome any present obstacles to the
progress of the art."

The Deficiency Bill to provide for the Army's
needs at that time carried an appropriation of
only $54,000,000 for aeronautics.

Appreciating the fact that the plans for the
building of our Air Forces on a scale propor-
tionate to the need were restricted by lack of
prospects to get sufficient appropriations and
believing that the American ])ublic would favor
the adoption of a plan extensive enough to pro-
vide for the training and ecjuipping of ten thou-
sand aviators and sending tens of thousands of
aeroplanes to the Allies, the Aero Club of
America undertook to get public support for
such a plan.

The canipaign started a few days after
the announcement of the Aircraft Production
Board. The slogan "We m ust Strike Germani/
Through the Air" was adopted.

In the first statement Mr. Alan R. ITawley,
the President of the Aero Club of America,
pointed out that, "Germany's U-boat warfare
and the necessity of keeping the German Heet
Imttled up are occupying the navies of the Allies
and no decisive victory over the Germans is ex-
pected in naval actions in the near future.
Likewise advances against the Germans on land

are slow, and Germany has seemed able so far
to always throw new thousands of men and new
lines of trenches and countless guns to meet
the advance of the Allies. The only victories
on the part of the Allies so far have been as a
result of supremacy of the air, as a result of the
matching of skilful, daring Allied aviators
against German aviators and observation bal-
loons; the recent British and Italian victories
wei-e preceded by countless aerial fights in which
hundreds of aviators took part, and it was not
until the skies had been cleared of German avi-
ators and of German observation balloons — and
the Germans were thereby deprived of the
aerial eyes of the infantry, of the aerial scouts,
and the Allies' aviators, being masters of the air,
could follow the movements of the enemy and
locate their batteries and their strongholds, that
the victories became possible.

"While the United States is beginning to help
substantially now, effective help of the kind that
leads to permanent victory can only come at the
end of months of preparation, and in consider-
ing in which way we can best prepare to help to
achieve permanent victories it is found that the
aerial branch of the service affords the greatest
possibilities. British, French, Russian, Italian
and American authorities who have studied the
matter closely have come to the conclusion that
the addition of 10,000 aviators to-day to the
Allies' present aerial forces would insure blind-
ing the German batteries and preventing Ger-
man aviators from conducting operations over
or near the Allies' lines. An additional 10,000
aviators would make it possible to conduct aerial
raids on a large scale and to strike Germany in
the most vital places, to strike hard enough to
lead to permanent victories."

A billion .dollar appropriation was urged for
Army aeronautics. It soon became evident
that the pul)lic favored the appropriation of this
sum.

One of the most important factors in creating
favorable public sentiment for this appropri-
ation was the hearings held by the Senate Sub-
Committee on Military Affairs on the Shep-
pard-Hulbert Bill to create a Department of
Aeronautics. This brought forth the endorse-
ment of leading authorities of not only the plan

HISTORY OF UNITED STATES ARMY AERONAUTICS

217

to train thousands of aviators and build tens of
thousands of aeroplanes, but also strong general
endorsements of the Sheppard-Hulbert Bill.

The hearings began June 12th, and lasted for
two weeks. Those who testified before the Sen-
ate Sub-Committee of the House of Representa-
tives, and endorsed the plan to establish a De-
partment of Aeronautics, were as follows;
Rear Admiral Robert E. Peary: Major L. W.
B. Rees, of the British Royal Flying Corps,
member of the British Commission in the United
States; Howard E. Coffin, Chairman, Aircraft
Production Board; Brigadier General George
O. Squier, Chief Signal Officer, U. S. A.; Alan
R. Hawley, President, Aero Club of America;
Henry Woodhouse, Henry A. Wise Wood,
Augustus Post, Rear Admiral Bradley A.
Fiske ; Lieut. Rumsey and Lieut. Prince, mem-
bers of the Lafayette Flying Corps; J. Bernard
Walker; F. H. Allen, one of the Directors of
the Lafayette Flying Corjjs; INIajor General
Goethals; Joseph A. Steinmetz, President of
the Aero Club of Pennsylvania.

The forceful statements made by these au-
thorities were pubhshed daily by the press
throughout the United States and brought out
hundreds of editorials urging prompt action and
large appropriations.

Brigadier General George O. Squier, the
Chief Signal Officer of the Army, in endorsing
the aerial preparedness program said, in part:

"The way to beat Germany is to flood the
air with aeroplanes. Take the war out of the
trenches and off the ground. Put it in the air."

On June 18th Secretary Baker came out for
a vast air fleet.

"The War Department is behind the aircraft
plans with every ounce of energy and enthusi-
asm at its command," said Secretary Baker.

"The aircraft program seems by all means
the most effective way in which to exert Amer-
ica's force at once in telling fashion.

"We can train thousands of aviators and build
thousands of machines without interfering in the
slightest with the plans for building up our
armies and for supplying the allies with food
and munitions. To train and equip our armies
and send them abroad will take time, however,
and in the meantime we can be devoting to this

most important service vast quantities of pro-
ductive machinery and skilled labor which other-
wise could not be contributing to the nation's
cause in full proportion to its capacity.

"The aircraft j)lans meet the demands of the
situation. Under existing conditions of fight-
ing, where the allies and the Germans are fight-
ing on practically even terms as regards man
power and aircraft, the addition which we can
contribute to the allied air forces will be propor-
tionately of far greater value than the immediate
aid which we can furnish on land. According
to the best obtainable information, there are
about 7,000,000 men on the western front to-
day. The addition of a few infantry units,
while of great moral value, is of little use in
forcing a decision. A few thousand trained
aviators, however, with the machines for their
use, may spell the whole difference between vic-
tory and defeat. The supremacy of the air, in
modern warfare, is essential to a successful
Army. America must make sure that the Al-
lies and not Germany, secure the permanent
domination of the air, and that within the
year."

On June 22 President Wilson himself en-
dorsed the movement, in the following letter to
Secretary Baker:

The White House,
Washington.
My Dear Mr. Secretary:

I have your letter of yesterday about the produc-
tion of aircraft and the training of men to operate
them, and want to say that I am entirely willing to
back up such a program as you suggest. I hope that
you will present it in the strongest possible way to the
proper committee of the Congress.
Cordially and sincerely yours,

(Signed) Woodrow Wilson.

Hon. Newton D. Baker,
Secretary of War.

A bill appropriating $640,000,000 was intro-
duced and passed the House of Representa-
tives on July 14, without a dissenting vote. It
passed the Senate on July 21, and was signed
by President Wilson July 24.

The estimate showed that only $363,000,000
was to be spent for aeroplanes, the rest going to
pay for the service squadron, supply squadrons,
training stations, machine guns, etc., and that

218

TEXTBOOK OF MILITARY AERONAUTICS

the number of aeroplanes to be ordered under
that appropriation would be only about 22,000,
a good portion of which would be training
machines needed for the training of aviators.

The Aero Club of America thereupon imme-
diately started a campaign to make known the
necessity of an additional appropriation of
$1,000,000,000 to build the thousands of large
warplanes needed to conduct major aerial op-
erations against the German bases.

Being told that the shortage of tonnage would
preclude shipping thousands of aeroplanes to
France, the Aero Club started to develop plans
for delivering the aeroplanes by flying them
across the Atlantic.

Aircraft Board Created

It became evident that to get quicker action
and remove confusion in the production of air-
craft it would be best to have an Air Board with
full authority, or better still, a separate De-
partment of Aeronautics. The Aero Club of
America had recommended the separate de-
partment of aeronautics in 1915, and urged it
continuously ever since.

Getting an Air Board with sufficient author-
ity the Aircraft Production Board and the
Signal Corps were prompt in acting and carry-
ing the plans into effect. Their work in estab-
lishing and putting into operation huge train-
ing aviation camps was extraordinary. Carry-
ing out the aircraft production program was
slower.

Among the most striking accomplishments
were the developing of the "Liberty motor" de-
signed l)y Messrs. J. C. Vincent and E. S. Hall,
and the creation of the International Aircraft
Standards Board with Mr. F. G. Diffin as chair-
man, was a step towards it. A bill to create
the Air Board was introduced in the Senate by
Senator Morris Sheppard of Texas and in the
House of Representatives by Congressman
^lurray Hulbert of New York. It passed the
Senate on September 12 and the House on Sep-
temljer 26. It was signed by President Wilson
onOctol)er 1st, 1917.

The act creating the Aircraft Board and the
endorsements of Secretary Baker and Secretary

Daniels may be found in "Flying" for Sep-
tember, 1917.

Unfortunately the provisions contained in
Section 4 and Section 5 of the Act confined this
Board to a merely advisory capacity and pre-
vented its getting an organization adequate to
do the important work of building Air Forces
extensive enough to cope with the fastly devel-
oping German Air Forces.

The following were appointed on the new
Aircraft Board: Howard E. Coffin, chairman;
Major-General George O. Squier; Colonel E.

A. Deeds; Colonel R. L. Montgomery; Ad-
miral D. W. Taylor; Captain Noble E. Irwin;
Lieutenant-Commander A. K. Atkins; R. F.
Howe, appointed November 6, 1917; and H.

B. Thayer, appointed February 26, 1918.
While these plans were being made in the

United States, two changes took place in the
situation in Europe, as follows:

1. Aerial warfare became more and more
intensified. Aerial combats became more nu-
mez'ous; the employment of aeroplanes to attack
infantry and artillery formations grew more
and more extensive; bombing at short- and
long-distance range became an every-day mat-
ter. This greatly increased the number of
aeroplanes in use, and more than quadrupled
the percentage of casualties among aviators and
the loss of aeroplanes due to different causes.

2. The Italian reverses and the Russian
collapse brought about serious conditions, ne-
cessitating a much greater contribution in air-
craft and aviators from the United States than
was planned and greater speed in carrying out
the plan. A committee of the Aero Club of
America, headed by Mr. Alan R. Hawley, the
])resident of the club, and including Congress-
man Murray Hulbert, Admiral I'eary, and the
writer, called on some of the Washington au-
thorities to urge the necessity. We found the
authorities divided in two groups: those who
felt certain that Congress would give additional
appropriations for aeronautics immediately
after convening in December; those who be-
lieved the program under way to be sufficient to
meet the changed condition, and would not con-
sider increasing it.

HISTORY OF UNITED STATES ARMY AERONAUTICS

219

It soon became apparent that the Russian
and Itahan reverses could have been prevented
had those countries had about two hundred
additional warplanes each, and that an auxiliary
air fleet was needed to meet the swift manceuvers
of the enemy. At the annual meeting of the
Aero Club of America on November 12, 1917,
the following resolution was adopted, which was
transmitted to President Wilson; Secretary of
War Newt(ni D. Baker; Secretary of the Navy
Josephus Daniels; Mr. Howard E. Coffin, the
chairman of the Aircraft Board; and Major-
General George O. Squier, the chief signal
officer :

Whereas, Tlio greatest difficulty of the Allies has
been to move their forces fast enough to meet unex-
pected German attacks on weak points of the Allied
lines, and to overcome the advantage which the Ger-
mans have of being able to transport large bodies of
troo])s, ammunition and supplies from one point to
another by interior lines ; and

Whereas, It is evident that powerful warplanes af-
ford the needed combination of power and mobility in a
higher degree than do any other appliances, and that
the recent occupation of the Baltic Islands by Germans
and the Italian reverses in the province of Venetia
could have been prevented if the Allies had been able
to send a sufficient number of torpedoplanes and bomb-
dropping aeroplanes to assist the Russians and Ital-
ians at the first evidence of danger ; and

Whereas, It is generally accepted by the recognized
authorities on aeronautics that aeroplanes can easily
be built which can fly across the Atlantic and thereby
solve the problem of delivering large units of aero-
nautic power to England, France, Italy and Russia,
without dependence on ocean transportation, or inter-
fering with it ; and

Whereas, There are in the United States unutilized
manufacturing facilities and resources which could
build thousands of powerful warplanes during the com-
ing year without interfering with the present aero-
nautical program of the Army and Navy; and

Whereas, These aeroplanes can conduct major
aerial operations against the German fleet and U-boat
bases, as well as against the German lines of communi-
cation and military industries and forces; be it

Resolved, That these facts be brought to the atten-
tion of the President, the Council of National Defense,
the Secretary of War, the Secretary of the Navy, the
Aircraft Production Board, and to the American pub-
lic, through the press, and that the coming Congress be
urged to expand the present aeronautical program by
appropriating not less than $1,000,000,000 for build-
ing an "Emergency Air Fleet" of huge warplanes, and

also appropriate $1,000,000,000 to carry out a com-
prehensive aeronautic program of training aviators
and building the tens of thousands of fighting, photog-
raphy, artillery and contract patrol aeroplanes ; dirig-
ibles and balloons, which are needed to assure the
Allies' supremacy in the air.

The $1,032,294,260 Army Air Program

In December, 1917, were made public the
Signal Corps estimates for 1919, in which was
asked the sum of $1,032,294,260 for aeronau-
tics, including the following items :

Lighter-than-air equipment

Aeroplanes and seaplanes

Spare parts and accessories

Extra engines and spare parts . .

Maintenance, upkeep, and opera-
tion of aero squadrons

Aero stations, United States . . .

Aero stations, Panama

Aero stations, Hawaii

Maintenance, repair, etc., build-
ings in Europe

Purchase of land

Warehouse and su])ply depots . .

Aviation clothing equipment ....

Expenses of officers, enlisted men,
and civilians on special duty . .

Vocational training

Mileage to officers and traveling
exjienses of civilian employees

Development of new types of
aeroplanes and engines

Schools of military aeronautics . .

Machine-guns for aero])lanes . . .

Photographic equipment, mate-
rial, etc

Contingent expenses, office equip-
ment, etc

Construction

Leasing of land

Reserve officers and men

Anemometers, barographs, avia-
tors' garments and other spe-
cial accessories

Miscellaneous

$8,171,000.00
235,866,000.00

47,173,200.00
553,289,120.00

20,950,000.00

20,400,000.00

5,420,000.00

4,420,000.00

9,127,000.00

16,700,000.00

5,595,000.00

1,358,440.00

67,200.00
120,000.00

3,050,000.00

2,000,000.00

8,050,000.00

77,475,000.00

3,405,500.00

100,000.00

$279,388.27

6,240,634.55

752,930.96

1367,110.95

1,249,120.62

70,462.39

3,061,293.77

77,512.13

400,000.00

2,841.45
358,314.90

Total aviation $1,032,294,260.00 $14,159,351.89

PAY OF OKFICKRS AXD MEN'

Pay of 11,941 officers $27,619,533.00

Aviation increase, officers ; 10,030,800.00

Additional pay for length of service, oflBcers .... 1 00,000.00

Pay of 153,94.5 enlisted men 60,606,607.05

Aviation increase, men 4,916,800.00

Additional pay for length of service, men 150,000.00

Total $103,423,740.05

Long Delay in Extending Plans and
Getting Appropriations Causes Trouble

It was most unfortunate that the necessity of
extending the aeronautic program was not rec-
ognized and steps were not taken to extend the
program in the autumn of 1917.

220

TEXTBOOK OF MILITARY AERONAUTICS

In official statements dated September 13 and
31, Secretaiy of War Xewtoti D. Baker an-
nounced the creation of the Liberty Motor and
the passing of its "final tests." On February
21, 1918, he announced that the first "American-
built battleplanes" were en route for France.

In March and April, 1918, it was made pub-
lic that the aircraft program was late by several
months.

The following letter, written by Mr. Alan R.
Hawley, president of the Aero Club of Amer-
ica, to President Wilson, on April 2, 1918, gives
the status of the situation at the time, and the
recommendations made to solve the problems:

Mif dear Mr. President:

A niimlHT of men who had applied for admission in the Air
Service of the Army have advised tlie Aero Cluh of America that
they have Iwen notified hy the Signal Corps autlioritics that no
further enlistments are heinp accepted at this time.

As Secretary Baker's rejwrt, published recently, stated there
were less than four thousand aviators under training, and know-
ing that it will take twenty thousand aviators to keep five thou-
s»nil aviators on the fighting front continuously for one year,
and realizing that to lack the trained aviators to supply the
necessary replacements would mean defeat for the cause of the
Allies, we were amazed to find this condition.

In answer to our inquiries, we were advised that the reason no
further enlistments arc accepted for the Air Service is that there
is a lack of training fields and of aeronautic equipment and that
these cannot he provided heeause there are no funds available
for the extension of the Air Service.

This is only one of the evidences that the aircraft program is
slowing down l>e<"ause of lack of funds. We have been advised
by factories that have completed their orders that they also do
not have orders to look forward to and to prepare.

We submit, Mr. President, Ihat this is a mournful condition
which threatens the cause of tlie .\llies more seriously tlian any-
thing else. Supremacy in the air is to be the key to victory. To
achieve and maintain supremacy in the air, the Allies must be
able to count on not less than twenty-five thousand American
aviators, .so as to insure keeping five thousand at the front con-
tinuously for the various duties of the Air Service and for the
iHimliing expeditions.

Tlie [H-rcenlage of replacements needed in the Air Service has
increased greatly in the past six months and will further in-
crea.s*' in tlie coming year, becau.se there is mii<-h more aerial
fighting, attacking troops from the air, bomliing at low altitudes
.ind night raiding. Aerial fighting is becoming more and more
intense; and the anti-aircraft guns are firing more and more
accurately anil hitting aeroplanes at altitudes of sixteen thou-
sand feet. This increases the casualties among aviators enor-
mously.

Thiii condition to-day is analogous to the condition which
exi>le<l last ()<'tol>er in the American aircraft situatiim as a
wlwlc. A largi- numU-r of training camps had b«vn estalilished,
at a cost of i^«K),(KK»,(KH), orders for aeroplanes and motors had
l)c«-n placed, and the funds had practically been exhausted.
Tliereu|Mm the work of developing additional sources of sui)plies
for aircraft and motors practically slopped, notwithstanding the
fact Ihat the Italian reverses and the Uussian collapse demanded
lni|>rrafively Unit our program Iw tripled in siw.

TIm' Aero Cluh of America officials urged aiul pleaded for
prompt omsiderntion of this new condition at the time, and
pointed out that It was aiisolutely necessary to immediately give
two l>ill)4>n dollars addilioiinl a])propriations for extending the
aircraft program. That wa« f>ix inontliii ago, when prompt

action would have prevented the confusion and mistakes which
were subsequently made, partly owing to lack of sufficient ap-
propriations.

Tlie main cau.se of tlie present deploralile condition of our
aircraft program was that tlie authorities in charge tried to
make twenty thousand aeroplanes do the work of eighty thou-
sand. The original program did not take into consideration
that it takes an average of two aeroplanes to give an aviator
the one hundred hours of preliminary and advanced training
needed to make him fit for the present-day highly specialized
work of a military aviator. Xor did it take into consideration
that it takes close to one hundred per cent, replacements per
month in aeroplanes and motors to keep aviators equipped for
fighting. Xor did it take into consideration that it takes forty
per cent, replacements in aviators per month to keep up the
fighting personnel of aero squadrons.

In making this program the fact was overlooked that if the
plan was to keep five thousand American aviators at the front,
it was necessary to train twenty-five thousand. Therefore, there
would be required fifty thousand preliminary and advanced train-
ing aeroplanes with which to train them speedily. The number
of aeroi)Ianes under construction to-day is not sufficient to even
give the preliminary and advanced training to the number of
aviators the I'nited States must supply within the coming twelve
months.

There was also overlooked the fact that to keep five thousand
aviators equipped for action, there would be required an average
of two thousand aeroplanes of different types per month, or a
total of twenty-four tlioiisand machines of different types during
the twelve months.

Having overlooked these very important considerations, the
authorities could not undertake to supply all the aeroplanes
needed out of the twenty-two thousand planned. The Italian
and Russian reverses created imperative needs, and the authori-
ties received caliles requesting thousands of aeroplanes of dif-
ferent types, l^acking the funds necessary to place additional
ortlers, the authorities changed the orders of aeroplanes under
construction, so as to meet the requests from France. As the
requests from France and the suggestions from the different
Allies were for different types of machines, the authorities kept
on changing the orders, so as to supply these machines for which
there seemed to be the most pressing need. This led to the
continuous changes which caused the set-backs which have re-
sulted in the aircraft program — which is still the same program
made at the time when Italy was victorious and Russia was
still fighting — being behind by several months.

Mad the authorities been in a position to place additional
orders whenever they received cables asking for a given num-
ber of machines of a given type, instead of having to change
orders for machines under construction, to-day the original pro-
gram would be nearly delivered and an additional program
would be well under way.

To-day we are making the same mistake that was made then.
We are stopping the enlisting of aviators and no .steps have lieen
taken to extend the program to meet the new conditions which
have arisen, and which, unless they are met ])r(nnptly, may result
in Allied reverses and )>ublic condemnation of your .Vdministra-
tion, not only from the .\niericaii pulilic liut also from the Allies.

It is tragic to us, .Mr. President, to know that while aeroplanes
and aviators are needed so badly to fight this figlit lor civiliza-
tion and humanity, hundreds of manufacturers who could lie
making aeroplanes and motor parts are kept in forced idleness
for lack of orders, and thousands of patriotic young men who
are anxious to join the Air Service and go to France and do
their share towards winning the war, are told that no further
men are lieing taken in the Air Services.

The delay in ])rodiicing the I.ilierty motor cannot be held re-
sp<msible for not giving preliminary and advanced training to
aviators. This training, which includes cross-country Hying,
boml)-drop])lng, shooting at moving targets from aeroplanes,
could be given with existing types of machines ami motors.

We submit, .Mr. President, that action must be taken pronqitly.

We agree with the memliers of Congress who advise us that
those in charge of the present aircraft program have failed to
make good and that it is hardly possible to expect better from

HISTORY OF UNITED STATES ARMY AERONAUTICS

221

the same organization if conducted hy the same authorities on
the ))resent plan of action.

W'c liave lollowod tlie aircraft program step by step and are
familiar witli tlic inside prol)lems tliat liave caused the delays.
TIk'sc causes are numerous, l)ul the main ones arc:

(I) Lacl< of concentrated rcsponsihility, authority and con-
trol in the management of aerial matters.

{'2) Lack of sufficient ai)proi)riations to extend tiie aircraft
program to meet the military needs of the Allies;

(;i) Lack of touch between the authorities dealing with the
strategic side o*' the war and the authorities iiaving charge of the
supplying of aircraft and aviators needed to build American
and Allied air forces.

(4) The lack of a Government department having the au-
thority and organization necessary to deal with all aircraft mat-
ters and ])revent delays due to division of res])onsil)ility, bu-
reaucratic jealousies and officials over matters of departmental
jurisdiction, duplication of efforts, etc. Tlie present Aircraft
Board is only an advisory board an<l has no jiowcr to act or to
get the necessary organization to extend or carry out an ex-
tended aircraft program.

To correct the situation, two successive steps must be taken,
as follows :

(1) The immediate appointment of an Assistant Secretary of
War and an Assistant Secretary of the Navy to represent the
Army and Xavy, respectively, in the Aircraft Board. This is
to solve the immediate problems while the second step is being
taken.

(2) The creation of a Department of Aeronautics, ba.sed on
the British plan, which i)laces the Air Services under a separate
Department of Aeronautics, the head of which is independent of,
although cooperating closely with, the War and Xavy De-
])artincnts.

The British Uovernment went through every one of the trou-
bles we have gone through in connection with our air service.
The official reports of the investigation of the British Air Service
in 191() shows that there were scandals and charges, counter-
charges and confusion, just as we have in the United States to-
day. After three years of trying different plan.s, the military
and naval authorities and other branches of the British Govern-
iiieiit came to the conclusion that the only solution was a .se])a-
rale Department of Aeronautics, with an Air Minister at the
head, whose functions are identical with the duties of the War
Minister and the First Lord of the Admiralty.

A separate Department of Aeronautics is the only solution to
all the problems of building the air forces needed to win the war.

We must add that many of tVie officials in charge of the air-
craft program and the members of their staffs arc able men
who, if placed in a Department of Aeronautics and given the
power necessary to act and to get together an efficient organiza-
tion, and the necessary funds, will quickly save the situation and
enable the United States to do its share in the air this year.

It is well to add that an important consideration that led to
the creation of the Air Ministry in Great Britain was the knowl-
edge that Germany is planning extensive aerial mail, express and

passenger transportation lines, to employ the output of her air-
craft factories after the war. Germany's plans are extensive
enough to employ tens of thousands of aircraft. This would
give her a reserve air fleet large enough to blow England, France
or Italy off the map overnight.

As was brought out in the House of Commons by Lord Mon-
tague, aircraft can be turned from vehicles of transportation to
war machines by the simple process of substituting bombs as
cargo. Any nation that overlooks this fact may pay dearly for
it overnight.

We all ho|)e, of course, that some agreement may be reached
between the nations which will guarantee against such a horror,
as the liombing of a nation out of existence overnight by another
nation having tens of thousands of aeroplanes. But the i)resent
war has shown that hopes do not save nations from the outrages
of aggressors. y\s a matter of fact, Germany's first air raids
of Great Britain were conducted by Zeppelins, which were em-
])loyed for ])assenger carrying before the war. So, while keeping
our hearts in the right place, we must be ready to i)rotect the
Republic and the rights of Humanity and the Cause of Civiliza-
tion. To do this will require direct control and supervision of
military and commercial air fleets, and this can only be done by
a well organized Department of Aeronautics.

In conclusion may we point out that in the past, events have
always proven that our suggestions, which were terme<l as ex-
cessive by some people at the time they were made, were most
conservative. We beg you to judge these recommendations ac-
cordingly.

Assuring you of the hearty cooperation of the Aero Club of
America and its affiliated Aero Clubs and cooperating organiza-
tions, 1 beg to remain

Very trul'- yours,

(Signed) Aiax R. Hawley,
President, Aero Club of America.

Following a report on the aircraft situation
made to President Wilson by G. Borglum, on
March 12 the War Department announced the
appointment of a committee on Aircraft Inves-
tigation, consisting of H. Snowden Marshall,
Edward Wells, and Gavin McNab. This com-
mittee reported its findings to President Wilson
in April. In the meantime the Senate Com-
mittee on Military Affairs investigated the air-
craft situation and reported on April 10. This
report was printed in full in "Flying," for May,
1918.

Memoranda:

The first flight, December 17, lOO;?. Orville Wrisht at the helm; \Vilber Wrifrlit alDiijrside of machine. Date, December 17,
1903. Time, 10:30 a.m., U:00 m. First flipht, twelve seconds. Longest flight, fifty-nine seconds. Wind velocity, twenty to twen-
ty-five miles per hour. Weight of machine, ()05 pounds. Total weight, with operator, 750 pounds. Power of motor, ten to twelve
horsepower. Weight carried per horsepower, sixty-three pounds. Speed of motor in flight, 1030 r.p.m. Speed of propeller, 3M)
r.p.m. Spread of wings, forty feet, four inches. Ix'ngth of chord, six feet, six inches. Total area of wings, 530 square feet.
Area of elevator forty-eight square feet. Area of vertical rudder, twenty square feet.

CHAPTER XVIII
THE EVOLUTION OF MILITARY AVIATION

As a matter of history, the first aeroplane
actually ordered by and constructed i'or a gov-
ernment was designed and built by Clement
Ader, the French pioneer, in 1890-97. ^Nlon-
sieur Ader, an electrical engineer by profession,
was an intense patriot, and after taking part in
the Franco-Prussian War of 1870, thought
France could have been saved from disaster by
an air fleet. Thereupon he set himself to study
the flight of birds, and having found an Indian
bat that .seemed easy to imitate, constructed a
large bat-like craft, which he fitted with a 40
horse-power steam motor and two propellers.
At the first trial in 1890, this machine, driven by
its own propellers, is said to have left the ground
in a jump. The French Government consid-
ered the craft of value, and engaged Ader on a
program which included nothing less than the
founding of an arsenal for the construction of
flying machines, the establi.shment of an aviation
sch(K)l, and the creation of an aerial fleet. For
this purpose a first appropriation of $100,000
was made.

The expectation proved disastrous to Ader,
for when he finished the first machine in 1897,

after six years of hard work, it did not fly and the
authorities refused to further finance the enter-
prise.

Subsequently, in 1905-06, the French Gov-
ernment negotiated with the Wright brothers
for the acquisition of their machine, but imposed
a condition that it should be guaranteed to reach
a height of 3000 feet. This was later modified
to 1000 feet. The Wright brothers, with their
usual caution, replied that they had never flown
higher than 100 feet, and rather than promise
what they did not care to prove, they let the ne-
gotiations drop. The demand it.self shows that
it was not suggested by actual knowledge of
aeroplanes, but deduced from performances of
balloons and dirigibles.

At about the time of Ader's experiment the
British Government became interested enough
to finance the experiment of Sir Hiram Maxim
in FiUgland. This inventor constructed a large
aircraft of the multiplane type, 120 feet from
tip to tip, fitted with two steam-engines of
175 horse-j)ower capacity, and weighing 7000
pounds. I>ike Ader's experiment, it was
wrecked in the attempt to fly it, and the military

222

THE EVOLUTION OP^ MILITARY AVIATION

223

authorities, who had been expecting to get a
practical craft out of the first experiment, were
disappointed and withdrew their support.

In 1908 the Board of Ordnance and Fortifi-
cations of tlie United States Army directed
Samuel P. Langley to construct a large-sized
model of the "aerodrome" he had designed, and
made an aj)propriation of $.30,000 to defray the
cost of the experiment. Langley's machine
was a tandem monoplane, 48 feet from tip to
tip and 52 feet from bowsprit to the end of its
tail. It was fitted with a .50 horse-power en-
gine and weighed 830 pounds. Two attempts
to launch it were made, one on October 7 and
the other on December 8, 1903. On both occa-
sions, according to reports, the "aerodrome" be-
came entangled in the defective launching ap-
paratus and was thrown headlong into the Po-
tomac River, on which the launching trials were
made. Following the last failure, when the
"aerodrome" was wrecked, the press ridiculed
the whole enterprise, and Congress refused to
appropriate money for further experiments.

The first requisition for a military aeroplane,
giving definite specifications of what the aero-
plane should accomplish to be acceptable for
military service, was made by the United States
War Department in an advertisement issued
December, 1907. This advertisement is a won-
derful document. It exacted the utmost, with-
out going into the impossible. It shows that
at that time — when Bleriot, Farman, and Cur-
tiss had only made a few jumps, and the per-
formances of the Wrights had not been made
public — the authorities at Washington had a
thorough knowledge of the aeroplane and a
lucid conception of its possibilities. The full
text of the advertisement is reproduced herewith
for its historical value:

Signal Corps Specification, No. 486

ADVERTISEMENTS AND SPECIFICATION FOR A
A HEAVIER-THAN-AIR FLYING MACHINE

To the pub ic:

Sealed proposals, in duplicate, will be re-

" ceived at this office until 12 o'clock noon on

February 1, 1908, on behalf of the Board of

Ordnance and Fortification for furnishing the

Signal Corps with a heavier-than-air flying ma-
chine. All proposals received will be turned
over to the Board of Ordnance and Fortifica-
tion at its first meeting after February 1 for its
official action.

Persons wishing to submit proposals under
this specification can obtain the necessary forms
and envelopes by application to the Chief Signal
Officer, United States Army, War Depart-
ment, Washington, D. C. The United States
reserves the right to reject any and all pro-
posals.

Unless the bidders are also the manufacturers
of the flymg machine, they must state the name
and place of the maker.

Preliminary. — This specification covers the
construction of a flying machine supported en-
tirely by the dynamic reaction of the atmos-
phere and having no gas bag.

Acceptance. — The flying machine will be ac-
cepted only after a successful trial flight, dur-
ing which it will comply with all requirements
of this specification. No payments on account
will be made until after the trial flight and
acceptance.

Inspection.— The Government reserves the
right to inspect any and all processes of manu-
facture.

GENERAL REQUIREMENTS

The general dimensions of the flying ma-
chine will be determined by the manufacturer,
subject to the following conditions:

1. Bidders must submit with their proposals
the following: (a) Drawings to scale show-
ing the general dimensions and shape of the fly-
ing machine which they propose to build under
this specification, (b) Statement of the speed
for which it is designed, (c) Statement of the
total surface area of the supporting planes.
(d) Statement of the total weight, (e) De-
scription of the engine which will be used for
motive power, (f) The material of which the
frame, planes, and propellers will be con-
structed. Plans received will not be shown to
other bidders.

2. It is desirable that the flying machine
should be designed so that it may be quickly and
easily assembled, and taken apart and packed

224 TEXTBOOK OF MILITARY AERONAUTICS

for transportation in army wagons. It should will be required of at least one hour, during
be capable of being asseml)led and put in opera- which time the flying machine must remain con-
ting condition in al)out one hour. tinuously in the air without landing. It shall

3. The flying machine must be designed to return to the starting point and land without
carry two persons having a combined weight of any damage that would prevent it immediately
about S.'iO pounds, also sufficient fuel for a flight starting upon another flight. During this trial
of 12.) miles. flight of one hour it must be steered in all direc-

4. The flying machine should be designed to tions without difficulty, and must be at all
have a speed of at least 40 miles pei- hour in still times under perfect control and equihbrium.
air, but bidders must submit quotations in their 7. Three trials will be allowed for speed as
proposals for cost depending upon the speed at- provided for in paragraphs 4 and 5. Three
tained during the trial flight, according to the trials will be for endurance, as provided for in
following scale: paragraph 6, and both tests must be completed

40 miles per hour 100 per cent. ^'t.^^'" ^ P^;""^ "f thirty days from the date of

39 miles per hour 90 per cent. delivery. The expcnsc of the tests is to be borne

S S: ;::; iZ ;:::::;;::;:::::::::; ;?o i::: Zl ^y t'^e manufacturer. The place of delivery to

36 miles per hour 60 per cent. the (iovemmcnt and trial flights will be at Fort

Less than 36 miles per hour rejected. JMver Virj>"inin

41 miles per hour 110 per cent. o Ti i i i l i •

*2 miles i>er hour 1:.>0 i.er cent. »• At Shouid DC SO dCSlgUCd aS tO aSCCud lU any

43 miles p<-r hour 130 per cent. countrv which may be encountered in Held serv-

44 nnles per hour 140 per cent. . * .

ice. I he starting device must be simple and

5. The speed accomplished during the trial transportable. It should also land in a field
flight will be determined by taking an average without requiring a specially prepared spot and
of the time over a measured course of more than without damaging its structure.

five miles, against and with the wind. The time 9. It should be provided with some device to

will be taken by a flying start, passing the start- permit of a safe descent in case of an accident to

ing point at full speed at both ends of the course, the propelling machinery.

This test is subject to such additional details as 10. It should be sufficiently simple in its con-

the Chief Signal Officer of the army may pre- struction and operation to permit an intelligent

scribe at the time. man to become proficient in its use within a rea-

6. Before acceptance a trial endurance flight sonable length of time.

Next the British Government engaged Sir Hiram Maxim to bulla :i mllil.ii) a. mpLiiK. Sir .Maxun's multipldnc ul>o < auic to

grief In an attempt to show its flying qualities.

THE EVOLUTION OF MILITARY AVIATION

225

11. Bidders must furnish evidence that the
Government of the United States has the lawful
right to use all patented devices or appur-
tenances which may be part of the flying ma-
chine, and that the manufacturers of the flying
machine are authorized to convey the same to the
Government. This refers to the unrestricted
right to use the flying machine sold to the Gov-
ernment, hut does not contemplate the exclusive
purchase of patent rights for duplicating the
flying machine.

12. Bidders will be required to furnish with
their proposal a certified check amounting to
ten per cent, of the price stated for the 40-mile
speed. LTpon making the award for this flying
machine, these certified checks will be returned
to the bidders, and the successful bidder will be
required to furnish a bond, according to army
regulations, of the amount equal to the price
stated for the 40-mile speed.

13. The price quoted in proposals must be
understood to include the instruction of two
men in the handling and operation of this flying
machine. No extra charge for this service will
be allowed.

14. Bidders must state the time which will be
required for delivery after receipt of order.

James Aixen,
Brigadier-General, Chief of Signal Officer of
the Army.

Signal Office,

Washington, D. C, December 23, 1907.

The Wright brothers were the only persons to
submit a complete machine and fulfil the require-
ments. The first trials, made by Orville
Wright at Fort Myer in September, 1908, re-
sulted in a record flight of 1 hour, 14 minutes,
20 seconds. An accident prevented the fulfil-
ment of the passenger-carrying requirement and
caused a delay of one year.

The Wright machine, which fulfilled the con-
ditions in August, 1909, was the old-type
Wright biplane. It had a spread of 40 feet, a
25 horse-power motor, front elevator, skids in-
stead of wheels, and was started by catapult and
monorail. The record flights made during the
tests at Fort Myer included a flight of 1 hour,
20 minutes, 30 seconds, and one of 1 hour, 28

minutes, 20 seconds, with Lieutenant Frank P.
Lahm as passenger.

It was most appropriate that the distinction
of supplying the first aeroplane to the United
States Government should have gone to the
Wrights, who gave the world the first practical
aeroplane. Wilbur Wright and his brother,
Orville Wright, two men of remarkable char-
acteristics, sons of the Rev. Milton Wright,
were presented in their boyhood, thirty odd
years ago, with a toy helicopter, a butterfly-
shaped contrivance, consisting of paper wings
fitted with a tin propeller which, when made to
revolve by twisted rubber, caused the toy to
shoot forward through the air. That toy fired
their imagination, and they saw it, in magnified
form, capable of carrying a man.

Their attempt to fly large helicopters con-
structed on the idea of the toy did not bring
practical results, and until 1896 they did not
give the matter of artificial flight more than
passing attention. In the summer of that year,
however, the news of the accident and death of
Otto Lilienthal, the German champion of glid-
ing flight, stirred them to action, and they set
themselves to study aerodjmamics and the works
of Lilienthal, ]\Iouillard, Chanute, Maxim and
Langley, the most prominent experimenters at
that time.

Their experiments with a glider began in the
autumn of 1900 at Kitty Hawk, North Caro-
lina. There, on the barren sand-dunes of North
Carolina, these two intrepid investigators took
all the theories of flight and tried them one by
one, only to find after two years of hard, dis-
couraging work, that they were based more or
less on guesswork. Thereupon they cast aside
old theories and patiently put the apparatus
through innumerable gliding tests, ever chang-
ing, adding, and modifying. They set down
the results after each glide, comparing and
changing details again and again, advancing
inch by inch, until they at last developed a glider
wonderfully exact, which, when fitted with -a
light motor also built by them, made initial
flights on December 17, 1903, of from twelve to
fifty -nine seconds' duration. This, then, was
the birth of the aeroplane, — the flimsy, icono-
clastic thing which seems to evade Newton's

226

TEXTBOOK OF MILITARY AERONAUTICS

The first "gun-plane" was the French Voisin armored and armed with a 37 mill, gun, Itbled early in liHi. It (li.-.jinnru iljc

theory that the recoil of a gun would upset the aeroplane.

laws, eliminates frontiers, and promises to ex-
pand civilization as much as have the steamship,
the railway, and electricity.

On September 15, 1904, Orville Wright,
flying the Wright biplane near Dayton, Ohio,
made the first turn in a heavier-than-air ma-
chine. On September 20, he made the first
circle; on October 4, 1905, he made the first
flight of over half an hour, a flight lasting 33
minutes, 17 seconds.

The Wrights did not make their achieve-
ments public at the time; in fact, until 1908
they flew only in private.

The report of their wonderful achievement,
nevertheless, spread far and wide. It stimu-
lated those who had given up experimenting and
inspired others to take up experiments. Octave
Chanute, in 1902, went to France and related
the early successes of the Wrights with their
glider, describing the general shape of the
Wright machine. The result of this trip was
that half a dozen enthusiasts, including Louis
Bleriot, Captain Louis Ferber, Ernest Arch-
deacon, and later the Voisin brothers and Al-
berto Santos-Dumont, took up the work, thus
founding the mighty French school, which has
increased so greatly and done so much ever since.
The first member of this school to succeed was
Santos-Dumont, the Brazilian aeronaut sports-
man. He constructed a machine of original
design, and in 1906 made short sustained flights
of from fifty to seven hundred feet in a straight
line. This created a world-wide sensation at

the time. Meanwhile, others of the French
school graduated and won honors. The Voisin
brothers became constructors and teachers, and
with their cooperation Leon Delagrange, Henry
Farman, Louis Bleriot, and others, prosecuted
practical experiments and succeeded in getting
their creations to leave the ground for modest
flights. At this juncture, during the summer
of 1908, the Wrights started to give pubhc
demonstrations. Their methods supplied and
suggested to the French experimenters the
means to modify and improve their aeroplanes,
particularly the method of balancing them,
which had, until then, been a perplexing prob-
lem.

The conditions set by the United States Gov-
ment in its specification of 1907-08 formed the
standard by which most governments judged
aeroplanes acquired for military work until the
close of 1911, when the French Military Com-
petition took place. This competition was or-
ganized by the French War Department at the
close of 1910, after the military manoeuvers, with
a view to develop better aeroplanes for military
purposes. The conditions to be fulfilled by the
competing aeroplanes and the prizes to be
awarded to the winners were as follows :

General Conditions of French Military
Competition of 19101911

1. The aeroplane and its engine must have
been constructed in France of the best ma-
terials.

THE EVOLUTION OF MILITARY AVIATION

227

2. Each aeroplane must make a circular
flight of 300 kilometers (186 miles) without a
stop.

3. Each aeroplane on this circular flight must
carry a load of 300 kilograms (660 pounds) over
and above the requisite petrol, oil, water, etc.

4. JMachines must provide accommodation for
three passengers: the pilot, a mechanic, and an
observer.

5. The mean speed must be not less than 60
kilometers per hour (37.3 miles) .

6. Machines must be able to land without dif-
ficulty or damage on plowed fields, meadows,
stubble, etc., and must start again from ground
of this character,

7. Machines must be easily transportable,
whether packed or not, by road or rail, and
should be easily assembled.

The following hints were given to construct-
ors:

1. It is desirable that the aeroplane be fitted
with a double control; or, at all events, that the
pilot and his assistant should be able to relieve
one another by taking over the control in flight.

2. It is desirable that machines should be ca-
pable of starting without outside assistance.

3. The observer's field of vision should not be
obstructed by any parts of the machine.

with their full load. The final classification will
be made according to the best performance dur-
ing this test.

PRIZES

The prizes will be awarded as follows: The
machine accomplishing the best performance
will be bought by the Ministry of War for the
sum of 100,000 francs and its constructor will re-
ceive an order for 10 machines of a similar type
at 40,000 francs each. An extra premium of
.500 francs will be granted in addition for each
kilometer of average speed above 60 kilometers
per hour that the machine has attained. The
constructors of the machines accomplishing the
second and third best performances will receive
orders for six and four machines respectively, at
the same prices. In the case where only two
machines come through the tests satisfactorily,
the constructor of the first will receive an order
for twelve machines and the constructor of the
second an order for eight machines ; and if only
one machine has satisfactorily passed the tests its
constructor will receive an order for 20 ma-
chines.

The genei'al conditions of this contest were

i';'f4'-l>*ss'''

-irnm?T^^m

PRELIMINARY TESTS

1. Three flights must be made with the above
stated load on board, and a landing accom-
plished on ground of the nature indicated in
paragraph 6 above. On each occasion machines
must reascend, start from the ground and land
again after a flight of a few minutes.

2. The machine carrying its full load must
make a flight over a circular course for the pur-
pose of testing its speed.

3. Two altitude flights, with the full load,
must be made, during which machines must
reach a height of 500 meters (1640 feet) within
15 minutes.

TWO FINAL TESTS

On a day appointed beforehand all the ma-
chines that have successfully passed the prelimi-
nary tests shall make a non-stop flight over a
circular course of 300 kilometers (186 miles)

How they tried to shoot over the propeller up to 1915, before
the method of synchronl/.inf; the gun with the propeller to per-
mit shooting through it was found, a French improvement.

228

TEXTBOOK OF MILITARY AERONAUTICS

French Caudron biplane equipped with two motors. (Official French photo.)

over 100 per cent, more severe and more detailed
than the general conditions of the American
competition. The aeroplane had been tried in
the military manoeuvers of 1910, and from its
accompli-shments the authorities had deduced its
great possibilities — if further developed — to
give the amount and quality of service exacted
as minimum in the competition. The conditions
show that the authorities had a thorough knowl-
edge of what an aeroplane would have to do to
suit for general military work, and the large
prizes offered show that they were aware that to
develop the required standard efficiency was to
involve lengthy and costly experiments, which
few of the constructors could carry out unless a
liberal inducement was given. As it was, the
contest had to be postponed for six months to
give an opportunity to constructors to develop
the required qualities.

Encouraged by the inducements given, six-
teen French constructors built special aero-
planes, thirty-four in number, whose general
characteristics were as follows:

Make

Type

Span Length Motor

„p Weight
^^- Kilo.

Antoinette Monoplane
Aktra Biplane

'■ Triplane

Antra-Wrlght Biplane
Bitriot Monoplane

Brtgnet

Biplane

Deperduuio Monoplane
U. Karman Biplane

M. Pannan

OoupT

Moru>*-Bor«l Monoplane

52' 6"

40'

43'

52'

36'

63'

41' 4"

63'

41' 4"

53'

40' 6-

39' 0"

40' G'

64'

62' 10"

64'

41'

44'

36'

34' 3"

31'

34'

27'

20'

28' G"

29'

28' 6"

29'

80'

30' .

30'

38'

82' 6"

82'

87' 8"

88'

83'

Antoinette

Chcnu

Renault

GnAme

Dancette

Canton-Une
It <(

OnOme
Anzanl
ClergPt
Renault

OnAme

Renault

Cbenu
OoAma

100

130

100

130

100

110

100

180

936
862
760
G24
4G5
515
652
637
652
722
703
700
462

626
691
691

471
689.B

618
637

Make

Type

Span

Length

Motor

H.P.

Weight
Kilo.

Nieuport

••

41'

29'

100

483

41'

29'

100

483

Paulhan

Triplane

41'

33'

Renault

R E P.

Biplane

30'

33'

R. E. P.

Savary

62'

38'

Labor

708

««

62'

38'

708

Voisin

48'

33'

GnOme

130

622

48'

33'

Renault

674

48'

33'

674

Zodiac

48'

32'

674

The final tests were held over the 300-kilo-
meter course from Rheims to Amiens. Adverse
weather conditions made these tests much harder
than they should have been otherwise, but helped
the aviators to show the good qualities of their
machines. Eight passed the tests successfully.
The machines, pilots, and speed attained were as
follows :

Pilot

Weyraan
Moineau
Prevost
Bregi
Fischer
Barra
Renaux
Frantz

Machine
Nieuport i
Br^guet 2
Deperdussin i
Breguct 2
H. Fa nil an 2
M. Farinan 2
M. Farman 2
Savary 2

Motor
Gnome
Gnome
Gnome
Gnome
Gnome
Renault
Renault
Labor

Time for 300

Kilometers
hrs. 33' 52%"
hrs. 9' Hi%"
hrs. 21' 5"'
hrs. 2(i' 47"
hrs. 33' 5"
hrs. 56' 13%"
hrs. 8' 40"
hrs. 27' 48"

Av. Speed
116.976
95.1
89.515
87.047
8i.474
76.196
72.38
67.210

1 Monoplane.

2 Biplane.

Thus in the short space of two years the mili-
tary aeroplane had been developed mechanically
from an experiment to a thing which gave serv-
ice of a kind which no other instrument or
mechani.sm could give. Its possibilities had
been defined and its purposes had been extended
^and made it a valuable military unit.

Following the French military competition
England, Germany, and Austria, organized
competitions of similar character. England,
who had not until then taken steps to introduce
aviation in the military establishment, organized
a competition to take place during the year 1912,
whose conditions were close to 100 per cent.

THE EVOLUTION OF MILITARY AVIATION

229

more severe than the conditions of the French
mihtary contest, as follows:

The prizes to be awarded by the War Office
on the recommendation of a Committee, which
will judge the tests and will decide whether
any machine submitted is to be subjected to any
test.

A. — Prizes open to the world for aeroplanes
made in any country :
First prize. .£4,000 Second prize. .£2,000

B. — Prizes open to British subjects for aero-
planes manufactured M'holly in Great Britain,
except the engines:

First prize . . £l ,.500 Two 2d prizes . . £1,000
Three 3d prizes. .£500 each

No competitor to take more than £.5,000.
The War Office to reserve the right to vary the
proportions of totals under A and B between
the various prizes if the merits of the machines
warrant it, or to withhold any prize if there is
no machine recommended for it by the Testing
Committee.

The War Office to have the option of purchas-
ing for £1,000 any machine awarded a prize.

The owners of 10 machines which are sub-
mitted to all the flying tests and are not awarded
a prize to receive £100 for each machine so
tested.

Oil and petrol to be supplied free for the tests.

The place of delivery of aeroplanes entered
for the con]])etition will be announced later.

The following conditions are those required
to be fulfilled by a military aeroplane:

1. To be delivered in a packing case suitable
for transport by rail and not exceeding 32 ft. 9
ft. by 9 ft. The case nmst be fitted with eye-
bolts to facilitate handling.

2. Carry a live load of 3.50 lbs. in addition to
its eqm'pment of instruments, etc., with fuel and
oil for 4^/4 hours.

3. Fly for three hours loaded as in Clause 2
and maintain an altitude of 4500 ft. for one
hour, the first 1000 ft. being attained at the rate
of 200 ft. a minute, although a rate of rise of
300 ft. per minute is desirable.

4. Attain a speed of not less than 55 m.p.h. in
a calm loaded as in Clause 2.

5. Plane down to ground, in a calm from not

more than 1000 ft. with engine stopped, during
which time a horizontal distance of not less than
6000 ft. must be traversed before touching,

6. Rise without damage from long grass,
clover, or harrowed lands in 100 yards in a calm,
loaded as in Clause 2.

7. Land without damage on any cultivated
ground, including rough plowed, in a calm,
loaded as in Clause 2, and pull up within 75
yards of the point at which it first touches the
ground when landing on smooth turf in a calm.
It must be capable of being steered when run-
ning slowly on the ground.

8. Be capable of change from flying trim to
road transport trim, and travel either on its own
wheels or on a trolley on the road ; width not to
exceed 10 ft.

9. Provide accommodation for a pilot and ob-
server, and the controls must be capable of use
either by pilot or observer.

10. The pilot and observer's view of the coun-
try below them to front and flanks nmst be as
open as possible, and they should be shielded
from the wind, and able to communicate with
one another. ;

11. All parts of aeroplane must be strictly in-
terchangeable, like parts with one another and
with spares from stock.

12. The maker shall accurately supply the
following particulars, which will be verified by
official test: (a) The h.p. and the speed given
on the bench by the engine in a six hours' run.
(b) The engine weight, complete (general ar-
rangement drawing), and whether air or water-
cooled, (c) The intended flying speed, (d)
The gliding angle, (e) Weight of entire ma-
chine. (/) Fuel consumption per hour at de-
clared h.p. {g) Oil consumption per hour at
declared h.p. (h) Capacity of tanks.

13. The engine must be capable of being
started up by the pilot alone.

14. Other desirable attributes are: (a)
Stand still with engine running without being
held. Engine preferably capable of being
started from on board, (h) Effective silencer
fitted to engine, (c) Strain on pilot as small
as possible, (d) Flexibility of speed; to allow
of landings and observations being made at slow
speeds if required, while reserving a high acceler-

230

TEXTBOOK OF MILITARY AERONAUTICS

ation for work in strong winds, (e) Good
glider, with a wide range of safe angles of de-
scent, to allow of choice of landing places in case
of engine failures. (/) It is desirable that the
time and nunil)er of men required for the change
from flying trim to road trim, or packed for
transport by rail, and vice versa, should be small,
and these will be considered in judging the ma-
chine. The time for changing from road trim
and packed condition to flying trim to include
up to the moment of leaving the ground in flight,
allowance being made for difficulty in starting
engine, (g) Stability and suitability for use in
bad weather, and in a wind averaging 2.5 miles
per hour 30 ft. from the ground without undue
risk to the i^ilot. Stability in flight is of great
importance. (//) The packing case for rail
transport to be easily dismantled and assembled
for use, and when dismantled should occupy a
small space for storage.

The Kaiser's Prize for a Motor Competition

Until the French military competition, Ger-
many had done little to develop aviation. She
had concentrated all her efforts on the large
dirigil)les, and the only aeroplanes in Germany,
with the exception of the Etrich type, were
French tyi)es or copies of French and Wright
types.

But German aviators in the military ma-
noeuvers of 1911 clearly demonstrated the value

of aviation, and Prince Henry of Prussia, who
had hitherto sponsored aviation without sup-
port, urged an appropriation of $7,500,000 for
aviation. As a result of the good work of the
German aviators, on January 27, 1912, the
Kaiser offered a prize of .50,000 marks to en-
courage the development of German aero-
motors. The letter offering the prize read as
follows :

To develop aviation in Germany, I desire to offer,
out of my private purse, a prize of 50,000 marks, to
be given on the occasion of my next patron saint's
day, January 27, 1913. The contest, examination,
and tests will be arranged and conducted by a com-
mittee composed of members of the Imperial Automo-
bile Club, Imperial Aero Club, members of the German
Automobile Constructors' Association, and delegates
of the Imperial Office of the Interior, the Navy, War
Department, Department of Public Instruction, and
Polytechnic School of Berlin.

I write you to draw up and present to me the report
of the finding of the committee by the beginning of
January, 1913.

(Signed)
Berlin, January 27, 1912.

WiLUAM, I. R.

The offering of this prize was like a signal to
the German nation to take up the work of avia-
tion.

The Aerial League of Germany started a
public subscription which brought in 7,234,500
marks. The purpose of the league was to train
within the shortest time as large a number as
possible of aviation pilots, to form a reserve, and
to encourage the general development of avia-

PartUl riew of tbe 90 Frenrh a<-ru|ilaneg which participated in tlic first military aeronautic review— held nt Buc, I-'rance, in I9I3.

THE EVOLUTION OF MILITARY AVIATION

281

tion in Germany. Following are some of the
results obtained:

The number of pilots was 230 at the end of
1912; it increased to 000 by the end of 1913.
The constructors of aeroplanes numbered less
than 20 in 1912 : they increased to 50 by the end
of 1913. The developments due to the eflForts
of the Aerial League led the Reichstag to pass
a bill providing for an expenditure of $35,000,-
000 for military aeronautics during the next five
years.

During the first month of 1914 inducements
offered by the Aerial liCague of Germany led to
the breaking by German aviators of all world
records. By the middle of July the non-stop
endurance record was brought up to 24 hours,
12 minutes, by Reinhold Boehm, and the alti-
tude record to 26,246 feet, by Heinrich Oelrich.
Over one hundred other records similar to the
above were made. For instance, Basser and
Landsmann made continuous flights of 18 hours,
11 minutes and 21 hours, 49 minutes, repect-
ively. In one of these flights Landsmann cov-
ered 1335 miles, the longest distance ever
traveled by man in one day. Among the
records for altitude was that of 21,654 feet, made
by Otto Linnekogel.

The secret of these successes was the motor. —
a Mercedes, — developed as a result of the in-
terest created by the Kaiser's prize.

- Aeroplanes First Used for Military Purposes
W in the Italian-Turkish War

The first aeroplane to be used imder condi-
tions approximately warfare was the Wright
machine belonging to Mr. Robert J. Collier.
He was then president of the Aero Club of
America, and loaned his machine to the United
States Government for use on the Mexican bor-
der in 1911.

The first employment of aero])lanes in actual
war was in Tripolitania, during the Italian-
Turkish war in 1911.

French Aviation Developed by Public
Interest

It was in 1910, that the late General Stephane
Brun, French Minister of War, took steps to
develop aviation in France. In so doing he

overruled the objections of his staff, who con-
demned the aeroplane as practically useless, and
recommended concentration of effort on build-
ing dirigibles. Up to that time nothing had
been done to develop military aviation in France.

During that year General Brun arranged for
the participation of aeroplanes and dirigibles in
the French military manoeuvers, and also em-
ployed leading civilian aviators in these ma-
noeuvers. The innovation proved a great suc-
cess and created tremendous public interest.

The manoeuvers were followed by the "Circuit
of Eastern France," which also was a great suc-
cess. In that cii'cuit the aviators covcM-cd a dis-
tance of 500 miles, accomplishing what was then
considered impossible. The success of this cir-
cuit led to holding, in 1911, the Paris-Madrid
Race, the Paris-Rome Race, the European Cir-
cuit, and the British Circuit, in all of which
French aviators participated, carrying away the
most important prizes. These circuits were fol-
lowed by military manoeuvers in which French
aviators again gave a good account of them-
selves.

The Paris Aero-Show that winter was
thronged by an enthusiastic, patriotic public
which expressed its enthusiasm in many ways.
At the time of the show an estimate was before
the French Chamber of Deputies appropriating
11,000,000 francs for military aviation. That
sum seemed insufficient to the enthusiastic patri-
ots and they said so. The French Minister of
War who had succeeded General Brun thought
the sum sufficient, and explained that it was
much more than had been spent the year before
for this purpose. The patriots were not con-
cerned with what had been done the year before ;
they wanted aeroplanes now, and wrote long let-
ters to the newspapers. The press became in-
terested and came out strongly in support of the
demand for more aeroplanes, pointing to the
splendid Salon show as an example of what
French genius could do. People all over the
country became interested and went to the
Salon. The sight of fourscore aeroplanes ex-
hibited there and contact with the airmen who
had brought France new glory did the rest.
Presently the provinces joined in the fight, and
the Minister of War was just getting ready to

232

TEXTBOOK OF MILITARY AERONAUTICS

The first use of aero-
planes in war during the
Italian-Turkish War. An
Italian airscout is here
shown starting on a
scouting trip outside
Tripoli, Feb., 1912.

reply to .scores of memorandums from repre-
sentatives of different departments when the
ministry fell.

The advent of the new Minister of War, M.
Alexandre Millerand, at this critical juncture
was most propitious. M. Millerand believes in
aviation. Though a Socialist, he is intently pa-
triotic and believes that a nation should be well
armed against contingencies. His first move
was to announce his full sympathy with the
movement and to increase the appropriation for
military aviation to 3,000,000 francs. This set-
tled matters and pleased all concerned. Things
were about to quiet down when it became known
that Prince Henry of Prussia had advocated an
expenditure of $7,.'500,000 for aviation, and that
the Kaiser had offered a prize of .50,000 marks
to encourage the development of German aero-
motors.

Next it was made public that the makers of
the Deperdussin monoplane, the military aero-
plane with which Vedrines and Prevost had just
made two splendid records, and which Vedrines
had used to fly over the Chamber of Deputies
and drop handbills reading, "Give France More
Aeroplanes," had received a communication
from a leading German concern. It was an of-
fer to buy the rights to construct that machine
in Germany, but advised that in case the offer

was declined the German firm would go ahead
and construct the machine without permission.

These three events had a tremendous effect.
It was accepted as a challenge from Germany.
Old scores were brought up, and the old wounds
of 1870 were reopened. But the result was not
an outburst of antagonism, as might have been
expected. Little time was spent in talking
about the challenge. Interest turned at once to
the matter of getting means to make France su-
preme in the line in which she leads — aviation.

On February 11, 1912 a meeting was held at
the Sorbonne, which bids fair to become a his-
torical event. It was held under the auspices
of the Association Generale Aeronautiqiie in or-
der to devise plans to start a national movement
to make France supreme in aerial matters, and
was attended by the highest civil and military
authorities. The meeting was open to the pub-
lic, who poured in until the vast Sorbonne hall
was packed to its capacity. The following re-
port by the Frantz-Reichel, the French veteran
reporter, gives an idea of what happened :

Representative Gabriel Bonvalot began speaking.
With extended arms and a voice vibrating with patri-
otic emotion he made his appeal.

"France need.s the fourth arm," said he, "and at
once. The other side of the Rhine is preparing; it
is the Emperor who has given the war-cry. Let us

THE EVOLUTION OF MILITARY AVIATION

233

prepare against this; let us unite our activities and
efforts in a manifestation which will make our country
supreme in aerial armament.

"I don't cry unto you : 'Help us !' I cry unto you :
'help yourself.' We must have aerodromes; we must
have hangars, aeroplanes, and money. Let us take
stock and let each give according to his resources.
Little or much, gold or pennies, — it does n't matter.
What we want is the manifestation of your love of
country. Say, will you?"

The audience roared "Yes!" enthusiastically.

"Thanks," said he.

But he was unable to continue. The gathering was
in uproar, and each person was busy taking stock of
his resources.

The generals present gave their caps to the avia-
tors, and the latter went up and down the aisles. But
there were not enough caps, and the audience cried,
"More, more!" Ladies then took the military avia-
tors' caps and went around to collect. But again
these proved not enough. As the crowd in the gal-
leries was growing impatient, the military students
took their own caps and went around.

Following this touching and curious scene, the col-
lection was emptied on a table before the generals,
senators and deputies, who made piles of the gold,
silver, and copper, and added up the total. Gabriel
Bonvalot rose again and said:

"You have given 2274 francs. This is well. But
I have other good news to announce. While you were
giving, others gave, and here is what the General Aero-
nautical Association has collected for the Committee
jof National Aviation. Listen ! The Aerial Associa-
tion of Picardie, 5000 francs ; M. Jacques Balsan, at
Chateauroux, one hangar ; at Pau, another hangar for
four aeroplanes and a house for twenty military avi-
ators ; the committee of Orleans, one aeroplane for the
Fifth Army Corps ; the committee of Cher and Prince
d'Arenberg, three aeroplanes ; the committee of Pi-
cardie, one aeroplane; the committee of Charentes,
100 acres of land; the committee of Pointiers, two
hangars and an aeroplane; M. Henry Deutsch, one
aeroplane; and, finally, M. Michelin, 100,000 francs to
pay for the apprenticeship of young men whose per-
sonal means do not allow them to put their courage at
the disposal of the nation."

This announcement was received with a thunder of
acclamations.

Captain Bellenger, the pioneer military aviator,
representing the Minister of War, IVI. Millerand, spoke
next. He demonstrated with the authority of an of-
ficer and an aviator the important role played by the
aeroplane in war, and he recalled the painful experi-
ence of 1870, in order to make the people understand
the lesson — understand that they had been defeated
by the ignorance of the chiefs of the French army con-
cerning the movements and plans of the enemy. He

recalled Weissemboyrg, Froeschwiller, and other pain-
ful instances, and showed that if similar circumstances
recurred, they could not bring the same terrible con-
sequences, provided France had aeroplanes in her
army. He ended by quoting conclusive examples of
the role played by the aeroplane in actual warfare in
Tripoli.

Following him. Senator Reymond spoke on the ne-
cessity of giving France a strong aerial organization.
Then M. Millevoy spoke of the great value of the aero-
plane, of its convincing qualities in furthering peace
and making France aerially supreme.

M. George Clemenceau, though an invalid forbidden
by his doctor to take part in the event, was conquered
by enthusiasm and, an invalid no longer, rose and pas-
sionately urged the people to assist in the national
movement.

When, finally, the addresses were ended. Mile. Vix
of the Opera sang an air from the "Vivandiere," in
which all joined. And thus ended this historic meet-
ing.

On the day after the Sorbonne meeting the
daily newspaper "Matin" started a national sub-
scription with a contribution of .50,000 francs,
an example at once followed by the "Petit
Journal" and the "Petit Parisien," and subse-
quently by other publications throughout the
country. Soon donations came from all sides.
States, departments, cities, towns, villages, clubs
and universities; political, educational, indus-
trial, sportive, and social associations — all con-
tributed. In most cases the plan of contribution
was to give an army aeroplane which would bear
the name of the state, department, or body mak-
ing the gift. Large communities contributed
as many as six aeroplanes. In some poor com-
munities the inhabitants contributed five cents
each; in others school-children contributed one
cent each; in a home of destitutes the inmates
offered to go without certain necessities to con-
tribute a few cents each. Individual contribu-
tions varied in type from checks for 100,000
francs, given by some rich persons, to a month
of services offered by a nurse who did not have
any cash. They included songs written by
chansonniers of Montmartre fame, and the
statue "La Defense," donated by the famous
sculptor, Rodin. Inside of a month's time the
collected fund amounted to over 1,500,000
francs. The total of the French public sub-

234

TEXTBOOK OF MILITARY AERONAUTICS

scription at the beginning of the present war
was 6,114,846 francs.

Board of Governors, Aero Club of America:

Gentlemen — As per authorization of your Executive
Committee, dated May 19, 1915, and February 23,
1916, I have, with Messrs. Henry A. Wise Wood and
Henry Woodhouse, attended to the affairs of the Na-
tional Aeroplane Fund, and I take pleasure in pre-
senting herewith a brief report of the work of the
National Aeroplane Fund, and an audit of so much
of the fund as passed through the hands of the Execu-
tive Committee of the Aero Club of America.

This audit shows that the sum of .$171,031.17 was
received direct, $147,314.92 of which was disbursed to
carry out the purposes for which the money was sub-
scribed. Of the balance, which amounts to .$23,-
716.25, the sum of $20,876.76 is obligated for the
$20,000 set aside for the prizes for the National Aerial
Derby, prizes for model aerojjlane competitions, ex-
penses for the National Aerial Coast Patrol Commis-
sion, etc.

In addition to the sum so subscribed, there were
given to the National Aeroplane Fund aeroplanes and
a course of training for militiamen and civilians, for
the purpose of lieli)ing to build our aerial defenses,
valued at $94,000, which are not included with the
cash subscriptions to the fund.

In addition, the funds, aeroplanes, and training se-
cured for different states, in different ways, not shown
on the books of the fund, but all being the direct result
of the work of the administrators of the National
Aeroplane Fund, and being valuable for what they
contributed to the building of our aerial defenses,
amounted to about $109,300.

This makes the total cash value of the contributions
secured through the efforts of the administrators of
the .National Aeroplane Fund, for the upbuilding of

our aerial defenses and developing our aeronautic re-
sources, $378,381.17. The value of resources devel-
oped is hard to estimate.

Furthermore, by means of the National Aeroplane
Fund educational campaign, public interest was
aroused to demand of Congress suitable a])propria-
tions for aeronautics in the Army, Navy, Militia,
Aerial Reserve Corps and Coast Guard, which resulted
in the appropriation for the diff'.>rent services of the
sum of $18,000,000.

As can be seen from the reports covering the differ-
ent lines of activity developed by the National Aero-
plane Fund, which was started in the spring of 1915,
when American aeronautics was at its lowest ebb, the
National Aeroplane Fund succeeded in developing
aeronautics in the Army, Navy, National Guard, Na-
val Militia ; among college men, in the Coast Guard,
and a dozen other fields.

This movement was started in the early spring of
1915, after Congress had adjourned and the inter-
national situation grew serious enough to make this
country take stock of its defenses. There were at the
time only about a dozen aeroj)lanes in commission in
the Army and Navy combined, when we should have
had one hundred times that number, and there were
no prospects of relief, since the last Congress had al-
lowed but a fraction of the amount needed for aero-
nautics. The maneuvers of the National Guard and
Naval Militia of the states were being planned, but in
no case was an aeroplane to be employed — the reason
being that there were no funds available to pay for
aeroplanes or for training Militia officers in aviation.

The Aero Club of America, the National aeronautic
body, which has fostered the development of aeronau-
tics in America since 1905, realizing the necessity of
bringing immediate relief, decided to wait no longer
for the Government to do its duty. It took steps to
contribute materially toward })roviding aeronautical

The flr»t tractor liiplanc in America. Constructed l)y Captain Jiiims V. .Martin in August, 1911. 'Vhv first fliglit toolt place in
November, 1911, at Nassau Boulevard, I,. I. It was equipped with a 100 h.p. Gnome motor.

THE EVOLUTION OF MILITARY AVIATION

285

equipment and instituted the National Aeroplane
Fund for the purpose of developing our aeronautical
resources, oi-ganizing aviation units in the Militia of
the States, building an aeronautical reserve, and creat-
ing in a general way sources of supply of personnel
and equipment.

In the educational campaign, which was the back-
bone of the National Aeroplane Fund, which resulted
in 2,000,000 })ieces of literature being distributed dur-
ing eighteen months, the committee has had the hearty
cooperation of the press of the United States. We
have received an average of sixty clippings a day re-
garding the work of the Aero Club of America during
these eighteen months, including hundreds of editori-
als, not a single one of which spoke unfavorably of the
National Aeroplane Fund or the work of the Aero
Club of America.

The work of the National Aerojilane Fund has been
highly commended by leading Congressmen and Sena-
tors, and was favorably mentioned on the floor of the
House of Representatives. We have also been warmly
praised by Washington officials, also by the governors
and adjutants-general of the States and by hundreds
of contributors to the fund, and others.

Some of the most important movements started or
endorsed by the Executive Committee in connection
with the campaign to develop our aerial defenses have
been adopted and endorsed by the Administration and
are as follows:

The Council of National Defense, which was advo-
cated by the Aero Club of America and other organ-
izations cooperating through the Conference Commit-
tee on National Preparedness in May, 1915, was
adopted by Congress, and President Wilson has just
appointed the seven civilian members of the council,
which include two prominent members of the Aero
Club of America.

The organizing of the Council of National Defense
is undoubtedly the most important step taken so far
to develop real national preparedness. This country
as a nation has been like a house divided. There has
been practically no cooperation between the Govern-
ment, the industries, the patriotic organizations, and
the people. So our enormous resources and extensive
industries have never been coordinated as the best in-
terests of the nation demand. The Council is to do
the coordinating, and we expect that aeronautics will
greatly benefit from the coordination of our aero-
nautical resources which the council may bring about.

The large appropriation asked by the Aero Club
of America for aerial defense, which seemed excessive
when it was proposed, as it was six times greater than
the estimates submitted to Congress by the secretaries
of war and the navy, was adopted by Congress, and
close to $18,000,000 was allowed for aerial defense,
instead of ,$3,200,000 asked by the secretaries of war
and the navy.

The plan to organize an Aerial Reserve Corps pro-
posed by the "New York World" and the Aero Club
of America, was authorized on July 13 by President
Wilson, after a committee of the club's Executive
Committee called at the White House and recom-
mended the authorization of the plan.

The j)lan of the Aerial Coast Patrol was promptly
endorsed by President Wilson and the secretaries of
war and navy, and an appropriation of $1,500,000
has been ]iromised for putting the plan into effect.

Steps were taken to establish aerial coast patrol
units, and a complete unit was established at Port
Washington, Long Island — the Volunteer AerisJ
Coast Patrol Unit No. 1, organized by F. Trubee
Davison and eleven other patriotic young men. This
unit rendered valuable service in connection with the
"Mosquito Fleet" manoeuvers.

A Bill was introduced in the Senate to appropriate
the sum of $1,500,000 for establishing units of the
Aerial Coast Patrol under the auspices of the Navy,
and in connection with the Naval Militia and Naval
Reserves, but owing to the shortness of time, and the
pressure of legislative business, Congress could not
act upon it during the past session.

The plan to use aeroplanes in connection with the
Coast Guard, for the Life-Saving Service and Revenue
Cutter Service, first recommended by me five years
ago, and since advocated by the Aero Club of Amer-
ica, and substantially supported by Byron R. New-
ton, the assistant secretary of the treasury, has been
adopted by Congress.

The plan to use aeroplanes for mail-carrying, ad-
vocated by the Aero Club of America for several
years, has been adopted and the postmaster-general
has invited bids for mail-carrying over different
routes where there is now spent $330,000 for carrying
mail by other methods. This sum would be spent for
aeroplane mail-carrying if suitable bids could be ob-
tained. The post-office authorities are anxious to
put this plan in operation and are giving every en-
couragement.

The plan to interest the universities in aerial de-
fense, which the Aero Club of America has been car-
rying out in so far as it concerns aerial defense, and
which was frowned upon some time ago, has been fol-
lowed by a request from President Wilson to the heads
of the leading universities to consider ways and means
to arrange for the training in military science of stu-
dents in sixteen of the country's leading universities
and colleges under the auspices of the War Depart-
ment.

Our committee, with the cooperation of Robert
Bacon, offered a bonus of $50 for each Harvard un-
dergraduate who learned to fly and passed the F. A. I.
pilot tests. Twenty-one undergraduates took a
course; twelve have already passed the tests. We
have also offered three medals of merit to each of the

236

TEXTBOOK OF MILITARY AERONAUTICS

First use of aeroplane in
w,ir oonditions. Lieut, (now
Brifr.-Gen.) B. D. Foulois
and P. Pariuelee at Eagle
Pass, March, 1911, with the
aeroplane loaned to the
Army by Robert J. Collier,
President of the Aero Club
of America.

hundred largest universities, having a total of about
850,000 students, the medals to be awarded to the
three students who, by March 15, 1917, write the best
essays on (a) Military Aeronautics; (b) Mechanics
of the Aeroplane and Possible Technical Development
in Aeronautics; (c) Possible Application of Aircraft
for Utilitarian Purposes.

To foster progress in the technical branch of aero-
nautics and begin the Work of standardizing, the com-
mittee, at the request of Thomas A. Edison, organ-
ized the American Society of Aeronautic Engineers,
which now includes in its membership all the promi-
nent aeronautic engineers. The society is now being
combined with the Society of .Automobile Engineers,
and Motor-Tractor Engineers, and a new organiza-
tion being created which is to be called the American
Society of Automotive Engineers.

Appreciating the basic value of Pan-Americanism
from the standpoint of national defense, the commit-
tee started a movement to develop Pan-American
aeronautics. Alberto Santos-Dumont was invited to
conic to the United States to cooperate in this move-
ment. He came, and has been traveling through South
and Central America, as the club's representative, and
has already done some very constructive work. The
organization of the Pan-American Aeronautic Fed-
eration was a direct result of the work of the Execu-
tive Committee. This federation is already a most
powerful organization, and will be more so as time
goes on. A large Pan American Aeronautic Exposi-
tion is now being organized to be held next February,
Mr. Henry Woodhouse, who, with Mr. Henry A. Wise
Wood, has been the father of the Pan-American move-
ment, is raising the $10,000 needed for the Pan-

American Aviation Trophy, and prizes to be com-
peted for at Rio de Janeiro next summer.

Giving a national defense aspect to the sport of fly-
ing resulted in two score of sportsmen taking up
aviation and acquiring their own aeroplanes for use of
national defense in case of emergency.

The success of the aviation meet, held at Sheeps-
hcad Bay last spring, was a direct result of the work
of the National Aeroplane Fund. Remarkable rec-
ords were made at this meet, including non-stop flights
from Newport News to New York with passengers.

Subsequently, and with the hearty cooperation of
the " New York World," a flight was made from New
York to Washington, in which I was a passenger, for
the purpose of carrying to Washington a special
edition of the "New York World," which advocated
the training of 2000 aviators, wiiich plan was en-
dorsed by the governors of practically all the States.
This plan to train 2000 aviators was favorably con-
sidered by Congress, and when a letter sent to one of
the Congressmen with a copy of the "World" was read
on the floor of the House of Representatives, the
House applauded and the letter was ordered printed
in the "Congressional Record."

Subsequently, and with the hearty cooperation of
Rear-Admiral Robert E. Peary, Congressmen Kahn,
Lieb, Hulbert, and Senators Johnson and Sheppard,
and Government officials, an exhibition of four aero-
planes was held in Washington. It lasted about two
weeks and assisted greatly in educating the members
of both Houses and making them realize the necessity
of increasing the appropriations for aerial defense.

It was also through the interest created by the Na-
tional Aeroplane Fund that Mr. Ralph Pulitzer of-

THE EVOLUTION OF MILITARY AVIATION

287

fered the Pulitzer trophy, instituting the National
Aerial Derby, which is to take place annually, and for
which there has been set aside $20,0C0 to be given as
prizes, this sum being part of the contributions made
to the National Aeroplane Fund by Mr. Emerson Mc-
Millin, who requested that his contributions be spent
at the discretion of the Board for whatever purposes
the Board deemed best.

To interest the younger generation in aeronautics,
prizes were offered from the National Aeroplane Fund
for model aeroplane contests, in which more than
twenty model aero clubs in different parts of the coun-
try participated. Knowing that the Wright Broth-
ers themselves became interested in aeronautics
through a toy helicopter, we realized that offering
prizes to encourage the younger generation may re-
sult in finding geniuses who may eventually create, or
develop or invent something which will be of great
value to mankind. To interest the still younger gen-
eration, at the time when the National Educational
Association of the United States held its convention
in New York, steps were taken to interest in aeronau-
tics the 60,000 school teachers who attended the con-
vention. An aeroplane exhibition was arranged espe-

cially for the teachers, and they were given copies of
"Flying," donated by the publishers, containing the
history of the development of aeronautics from the
earliest ages ; and a diploma to be awarded to a pupil
in each school who writes the best composition on
aeronautics.

The foregoing is only a brief outline of what has
been accomplished by the National Aeroplane Fund.
It would take many pages to give the less prominent
achievements.

The committee received substantial and hearty sup-
port from the following governors of the club: Rear-
Admiral Robert E. Peary, Cortlandt F. Bishop, John
Hays Hammond, Jr., Evert Jansen Wendell, diaries
Jerome Edwards, Albert Bond Lambert, George M.
Myers, Henry B. Joy, Rodman Wanamaker, and the
late Samuel H. Valentine.

It is hard for me to find words that will adequately
express the value of the work done by Mr. Henry
Woodhouse in connection with the National Aero-
plane Fund. He subscribed the first $1000 to make
it possible to begin the National Aeroplane Fund, and
then made additional contributions during the cam-
paign. He has given his entire time, practically six-

jmm

'^y"-mmy^_ r-^ M

__ — : ^z!!32£*JBSLaH^HHHBI^^^^^I

Looking down on a German Gotha resting on the ground. (British official photo.)

238

TEXTBOOK OF MILITARY AERONAUTICS

teen hours a day, every day, including Sundays and
holidays, to this work, practically only leaving the
club house on occasions when he had to deliver ad-
dresses and to attend meetings or make trips of in-
spection in connection with the furthering of this
campaign. He has done this without compensation
or expectation of compensation.

Very sincerely yours,

Alan R. Hawley,
Chairman.

Firing Guns, Dropping Large Bombs, and
Two-Engined Aeroplanes Once Consid-
ered Impossibilities

The writer clearly remembers that in 1910-13
the firing of machine-guns and the dropping of
large bombs from aeroplanes were considered
impossibilities. It was lield that tlie recoil of a
gun would upset the aeroplanes ; while the drop-
ping of weight of more than fifty pounds would
upset the aeroplane. For that reason it was
held that aeroplanes could only be used for
scouting, directing artillery fire, and taking
photographs. The development of speedy aero-
planes was discouraged. Those who expressed
the possibility of equipping aei'oplanes with two
or more motors were considered visionary, the
general opinion being that an aeroplane
equipped with two motors would fail. Two

reasons were given: First, the machine would
be unable to lift its own weight ; secondly, if one
motor stopped, the other motor would make the
machine spin.

Speed in aeroplanes was developed, there-
fore, entirely by private efforts, mainly by
sportsmen and aero-clubs in connection with the
annual competition for the Gordon-Bennett
Cup. As early as 1912 this trophj' was won by
a flight of over one hour at a speed of 10.5 miles
per hour. In 1913 tlie winner of the Gordon-
Bennett Cup made a speed of 124 miles an hour
for about one hour.

In 1913 a prize of $15,000 was offered by Mr.
Edwin Gould, a member of the Aero Club of
America, in a competition for twin-motored
aeroplanes, but it was not won, although the
conditions required only a flight of about one
hour.

Following is given, for historic purposes, a
table of the performances required by the British
War Office for aeroplanes of different types on
February 9, 1914.

British Army Tests for Aeroplanes in 1914

1. The Chief Inspector of Military Aero-
nautics is prepared, on the request of an aero-
plane constructor, to put an aeroplane through

Onrille Wright and Lieutmant .S<-lfri<i(ff In tin- Wright Flyer, built for the U. .S. Army, on the (hiy of the trageily which cost
the Ufe of Lieutenant Selfrldge, who was the first man to be killed flying in an aeroplane.

THE EVOLUTION OF MILITARY AVIATION

28»

The Langley Aerodrome.

Then the United States Government commissioned C. P.
Langley to construct a man-carrying aerojilane. The "aero-
drome" was a remarliable advance step, but the experiments
were not concluded.

the ordinary military acceptance test under the
following conditions :

(a ) The test consists of examination of work-
manship and materials, speed test, fast and slow,
climbing, weight of load carried, rolling test,
and one hour's flight. The constructor must
supply the pilot and passenger. For purposes
of calculation weights of pilot and passenger
will be 160 lbs. each.

(b) Stress diagrams in duplicate for the aero-
plane must be sent with or before the machine.
A minimum factor of safety of 6 throughout is
essential.

the types used for military purposes. These
are given in attached table.

(d) The constructor, when applying to have
his machine tested, should state his reasonable
expectation of the performances of the ma-
chine.

(e) Aeroplanes submitted for test must be
put through the whole of the test unless dam-
aged before their completion, or unless the
Chief Inspector considers that the test should
be .stoi)i)ed for reasons of safety.

2. The Chief Inspector of Military Aero-
nautics is also prepared to examine and test
aeroplanes which may be designed not for
purely military purposes, but to demonstrate
some practical or theoretical improvement in
design or construction. The tests imposed in
such cases will be at the discretion of the Chief
Inspector.

3. Results of any test will be supplied ta
the constructor by the Chief Insi)ector, and
will be kept secret, if desired by the con-
stioictor. Should the constructor wish to pub-
lish the result of the test, it is to be understood
that the result should be published complete.
Should only part of any report of the test be
published, the Chief Inspector reserves the
right to publish it in full.

4. The satisfactory performance of the tests,
laid down in paragraph 1 does not constitute a
guarantee that the aeroplane in question will be
purchased by Government.

5. These tests may be altered from time to
time ; notice will be given as early as possible of
any alteration.

War Office,

February, 1914.

PERFORMAXCES REQUIRED FROM VARIOUS MILITARY TYPES

Tankage to give an en- Light Scout. Reconnaissance Reconnaissance Fighting Fighting

durance of Aeroplane (a). Aeroplane (6). Aeroplane (a). Aeroplane (6).

300 miles. 300 miles. 200 miles. 200 miles, 300 miles.

To carry Pilot only. Pilot and observ- Pilot and observer, plus SO lbs. Pilot and gunntr. plus Pilot and gunner, plus

V er, plus 80 lbs. for wireless equipment. 300 lbs. for gun 100 lbs.
for wireless 35 to 60 m.p.h. and ammunition.

equipment. 10 minutes. 45 to do m.p.h. 45 to 7S m p.h.

45 to 75 m.ph, 10 minutes. S minutes.

7 minutes, A clear field of fire in

Range of speed 50 to 85 m.ph To land over a 30-ft. vertical ob- A clear field of fire in every direction up

To climb 3500 feet in 5 minutes. stacle and pull up within a dis- every direction up to 30° from the line

Miscellaneous qualities Capable of being tance of 100 yds, from that ob- to 30° from the line of flight,
started by the stacle, the wind not being more of flight,
pilot single- than 15 m.p.h. A very good
handed. view essential.

Instructional aeroplanes with an endurance of 150 miles will also be tested under special conditions ; safety and ease of handling will ba

of first importance in this type.

240

TEXTBOOK OF MILITARY AERONAUTICS

The Clement Ader Avion,

In 1890-1897 the French
Government planned to
construct an aerial fleet
and enjraped Clement
Ader to do it. It was
the first time a jrovern-
ment had actually or-
dered an aeroplane for
military use. Ader's
^vion was wrecked in
the first attempt to fly.

Aeronautics at the Outbreak of the War
Germany's costly failure to employ aircraft

IN the BELGIUM INVASION

Although all aeronautic activities in Europe
before the Great War were of a military na-
ture, plans for the employment of aircraft for
military purposes were by no means extensive.
True, the largest European nations had be-
tween 500 and 2000 aeroplanes each, and some
of the powers, especially Germany, had fleets
of dirigibles and some observation balloons.
But military aeronautics was not a defined sci-
ence. Though there was no doubt about the
value of aircraft for scouting purposes, and an

expectation that Zeppelins could do awful dam-
age with their bombs, the general application of
aircraft for military purposes was mainly a mat-
ter of opinion. While some of the aeronautic
experts were good prophets, their opinion was
questioned by thousands of people who con-
sidered these experts visionaries. Military men
of the old school were slow to accept the value
of aircraft. As a matter of fact, the Germans
themselves suffered their greatest loss through
failure to recognize the value of aircraft and
through failure to employ them in their initial
campaign against Belgium.

There is evidence that Germany in her under-
estimation of the tenacity of Belgium did not
make use of her air scouts during the first period
of her campaign. She relied entirely on the

t)n<- i)f till' iiirly Kiismuti .Mkcirslty warplanes, the lirst iiuuluiii-.s Id r:\ir\ nuilUjili- power plnlll^.

THE EVOLUTION OF MILITARY AVIATION

241

overwhelming strength of her formidable army,
and did not consider it necessary to employ air
scouts to find vulnerable spots and offset the ad-
vantage gained by Belgium through the latter's
judicial employment of the able Belgian air
scouts. The Germans started in with a crush-
ing preponderance of men, but played the game
in accordance with plans made many years ago,
with little consideration for the immediate
moves of the enemy. Belgium, with few men,
but employing a score of efficient air scouts,
moved as circumstances dictated. The i-esult
was a comparatively large loss of men and in-
estimable loss of time on the part of the Ger-
mans. But for that loss, the Germans might
have gone through Belgium and on to Paris
before the French had time to complete their
preparations.

For the better part of the first year of the
war aerial operations were almost entirely con-
fined to scouting, directing artillery fire, and an
occasional raid. This was true of both the
heavier and lighter-than-air craft.

Then a logical expansion took place. Each
side tried to prevent the air scouts of the enemy
from reconnoitering and carrying back in-
formation they had gathered; also to prevent
enemy aircraft from dropping bombs over their
lines. This started a period of aerial fighting,
which has governed the supremacy of the air
ever since.

The side which has the best air fighters holds
the supremacy of the air on the fronts and, while
able to get information about every movement
of the enemy, has it in its power to prevent that
enemy from obtaining like information. Air
superiority may be said to be responsible for all
the victories on the different fronts in the pres-
ent war.

Next came the famous Boelke and Immel-
man with their high horse-powered Fokker
monoi)lane, merely a development of the French
Morane-Saulnier monoplane, equipped with a
160 horse-power engine. Boelke and Immel-
man would ascend 1.5,000 or 18,000 feet and
watch for an opportunity to pounce down on an
enemy aeroplane, shooting while diving down-
ward. These two crack German aviators
brought down a number of Allied aviators be-
fore the Allied commanders realized what was

happening. Then the Allies brought out their
very fast machines.

These included the famous Nieuport biplanes
and Sopwith speed biplanes, and these were
quickly followed by the "Spads" and other fast
machines. The Allies developed a great many
crack aviators, including Lieutenants Navarre,
Guynemer, William Thaw, Norman Prince,
Captain Hall, and other famous aviators.

A new development came with the employ-
ment of large aeroplanes, capable of carrying
hundreds of pounds of explosives. These were "
used by both sides to bombard enemy positions,
and made it necessary for each side to be ever-
lastingly on the watch to protect its cities and
bases from aerial attack, thereby withdrawing
man}' aviators from the fronts. But the num-
ber of aeroplanes employed was always too
small to permit achieving decisive victories
through reducing positions from the air.

The next development of importance, which
took place in 1916, was the employment of aero-
planes to perform the functions of cavalry, in
engaging the enemy and the anti-aircraft guns ;
also the functions of the artillery, in bombard-
ing and destroying trains, bridges, and bases;
and lastly the functions of the infantry, by fly-
ing low and attacking troops in the trenches or
along roads.

Advent of Large Warplanes in 1917 Per-
mitted Conducting Major Aerial
Operations

The advent of large warplanes in 1917 per-
mitted conducting major aerial operations.
The Italians set the precedent by conducting
numerous air raids on Austrian bases with their
large Capi'oni warplanes. (See chapter on
"Warplanes for Bombing and Launching Tor-
pedoes.")

Russia probably could have done the same
two years earlier by employing the large Sy-
korsky aeroplanes, but the Russian Govern-
ment did not have the organization or a clear
idea of the value of the large warplanes, and
the value of the Sykorskj' warplanes was lost in
a succession of failures due to lack of organiza-
tion When the Sykorsky machines were or-
dered to fly to the front from their base hun-

242

TEXTBOOK OF MILITARY AERONAUTICS

dreds of miles away, no provision was made for
landing-places along the route, and the field
from which they were to operate near the front
was not suitable for large machines. The re-
sult was that only two machines out of a dozen
survived the journey from the home base.

As the Sykorsky machines were slow, they
were best adapted for night work, but there was
no organization for work of this nature. There-
fore the machines were only used for day
operations, and in this style of fighting they
were no match for the smaller, but faster Ger-
man machines. Being slow, they were easy tar-
gets for the anti-aircraft guns.

The Italians began with a very efficient or-
ganization and a thorough appreciation of the
value of night operations. At first they had
only a small number of machines, but as fast as
they could build more they increased the num-
ber of their raiding squadrons. By August,
1917, they were able to send 232 aeroplanes in
one raid, during which they lost only one aero-
plane.

The United States Lagged Behind for
Seven Years

After gaining the distinction of owning the
first military aeroplane, the United States prac-
tically stood still, while other nations developed
large air fleets. From the time the first aero-
plane was purchased until 1916, the appropria-
tion for army aeronautics aggregated only
$600,000. The small sums allowed each year
were not sufficient to support even one manu-
facturer, and as orders were distributed among
a number of manufacturers, and the recjuire-
ments for aeroplanes changed with each order,
the aeroplane manufacturers did business with
the Government at a loss. During this period
the aeronautic industry was kept alive mainly
by civilian support and the hope of better times.

In 1915-16 the British Ciovernment placed
substantial orders with American aeroplane
manufacturers, totalling about $13,000,000, and
thereby developed the American aeronautic in-
dustry. But these orders were entirely for
training machines and sea-planes, and as there
was no demand for fast fighting-machines or
large lK)mbing-machines, these types did not get
beyond the experimental stage.

Aero Club of America's Monumental Work
in Developing Our Aerial Forces

Throughout these lean years the Aero Club
of America was the main factor in developing
our aerial forces. This patriotic organization,
which has fostered the development of aeronau-
tics in America since 1905, worked incessantly to
build up the air service. Through energetic ef-
forts it succeeded in having appropriations for
military aeronautics increased, and trained, or
caused to be trained, several hundred militia
and civilian aviators who later became aviators
in the Aviation Officers' Reserve Corps.

In 1914-15 the Aero Club of America
pointed out that with 5000 aviators this coun-
try would be in the position of the porcupine,
which goes about its daily pursuits, harms no
one, but is ever ready to defend itself.

When the 63rd Congress appropriated only
$250,000 for aeronautics during 1915, the Aero
Club of America authorized the institution of a
National Aeroplane Fund to develop our aerial
defenses. Some idea of the important accom-
plishments made possible by this fund can be
gained from the following excerpts from the re-
port presented to the Board of Governors of the
club by Mr. Alan R. Hawley, chairman of the
committee which had charge of this fund.

America's Entry into the War Brings Deci-
sion to Concentrate Efforts to Strike
Germany Through the Air

Following America's entry into the war, the
Council of National Defense created the Air-
craft Production Board, to cooperate with the
army and navy to increase the production of air-
craft for the United States, as well as for the
Allies.

While the Aircraft Production Board and
the military authorities were considering plans
to develop a substantial air sei-vice, the Aero
Club of America issued a series of statements
pointing out that an additional 10,000 aviators
would make it possible to conduct aerial raids
on a large scale and to strike Germany in vital
places, — to strike hard enough to lead to per-
manent victories. It recommended the appro-
priation of one billion dollars to carry out this

THE EVOLUTION OF MILITARY AVIATION

248

plan of striking Germany through the air.
Congiessman Murray Hulbert of New York
and Senator Morris Sheppard of Texas, who
had introduced a Bill to create a separate de-
partment of aeronautics, held hearings in the
Senate at which authorities testified to the im-
portance of aeronautics.

The statements of the Aero Club of America
and other authorities were published daily in the
press for about one month, and the leading
newspapers also sponsored the project to build
large air fleets. As a result, practically every
paper in the country gave editorial support to
the recommendations for a large appropriation
for aeronautics, and when the Bill to appropri-
ate $640,000,000, which had been approved by
Secretary Baker, came up for vote in the House
of Representatives on July 14, 1917, it passed
the House without a dissenting vote. The Sen-
ate passed it a few days later.

In the meantime, the Aircraft Production
Board and the Signal Corps had been develop-
ing plans for large aviation schools, so that they
were ready to start training aviators when the
appropriation became available.

The Problem of Delivering Aeroplanes to
Europe

The one serious problem is the delivery of
aeroplanes to Europe. To deliver 100,000
aeroplanes would probably take most of the ton-
nage at the disposal of the Allies, to the exclu-
sion of practically everything else. At date of
writing the Aero Club of America's plan to fly
the machines across the Atlantic is being con-
sidered.

British Air Ministry Created

The frequent l)oinbing raids on British soil, together with cer-
tain very evident disadvantages to which the Allies were put
through Great Britain's failure to bomb German manufacturing
centers, destroying German bases, railroads, and the bridges on
the Rhine, caused continuous criticism of the British Govern-
ment. This criticism became very severe in 1916, and an inves-
tigation of the British Flying Corps was instituted, which lasted
from Ma.y to August. As a result of this investigation, certain
changes were made in the management of the Royal Aircraft
Factory, and then, in February, 1917, the Air Board was created.

The members of the Air Board were: The Right Hon. Vis-
count Cowdray, President; Major J. I.. Baird, C. M. G., D. S. ().,
M. P., Parliamentary Secretary; Commodore Godfrey Paine,

C. B. .M. \-. C)., R. \., Director of Air Service (D. S. A.);
Lieutcnant-General Sir David Anderson, K. C. B.; Major-Gen-
eral J. M. Salmond, C. M. G., D. S. O., Director Cieneral of
Military Aeronautics (D. G. M. A.); Sir William Weir, Con-
troller of Aeronautical Supplies (C. A. S.); Mr. Percy Marin,
Controller of Petrol Engines (C. P. E.).

The Air Board had only limited power. It could only dis-
cuss matters of i)olicy in relation to tlie air program in general,
consider the programs of construction of aeroplanes and sea-
planes formulated by the Admiralty and the War Office, and
select and be responsible for the designs of aeroplanes and
seaplanes and their engines and accessories.

The |)olicy of not conducting major aerial operations against
the Germans continued with the new Air Board. As the Ger-
mans succeeded in maintaining their own on the Western front,
at the same time striking a heavy blow at Italy and Russia, the
criticisms of tlie British Govermnent due to dissatisfaction with
the management of aerial matters grew more and more severe.
Decision was then reached to establish an Air Ministry. Tliis
was done in November, 1017. The position of air minister was
offered by Lloyd George to Lord Northcliffe, who declined it.
It was then offered to Lord Rothermere, Lord NorthcliiTe's
brother, who accepted it.

The Air Council of the Britisli Air Ministry was established
on January 2, 1918. It was constituted as follows:

Lord Rothermere, Secretary of State and President of the
Council; Major-General Sir H. Trenchard, K. C. B., D. S. ().,
Chief of the' Air Staff; Rear-Admiral Mark Kerr, C. B. R. N.,
Dei)uty Chief of the Air Staff; Commodore Godfrey Paine,
C. B.," M. V. O., R. N., Major-General of Personn<h Major-
General W. S. Brancker, Controllcr-Cieneral of Equijuncnt; Sir
William Weir, Director General of Aircraft Production in the
Ministry of Munitions; Sir John Hunter, Adun'nistrator of
Works "and Buildings; Major J. L. Baird, C. M. J., D. S. ().,
M. P., Parliamentary lender-Secretary of State; Lieutenant-
General Sir David Henderson, K. C. B., D. S. O., Additional
Member of Council and Vice-President.

Mr. W. A. Robinson, C. B., has been appointed to act tem-
porarily as secretary to the Council, and Mr. H. W. McAually to
act as assistant secretary.

Sir John Hunter, K. B. E., will continue to perform his present
duties in the Ministry of Munitions, in addition to acting as Ad-
ministrator of Works and Buildings in the Air Ministry.'

Tlie German drive in March-April, 1918, emphasized anew
the importance of aircraft and the vital necessity of nuiintain-
ing aerial supremacy. In the meantime the price of maintaining
aerial supremacy had increased. Whereas in 1910 it took only
about twenty per cent. re))lacenients of aviators and fifty per
cent, of machines per month to keep aero squadrons on the front,
in 1918 it took over doul)le that number. This was due to higher
skill and more extensive aerial fighting; increase in day and
night bombing at low altitudes; increased efficiency of anti-air-
craft batteries, firing on troops from low-flying aeroplanes, etc.
In other word.s, to aim to keep 5000 aviators on the fighting-lines
for the year 1918-1919 involved su]i|)lying i?9,000 aviators, re-
quiring an average of two aeroplanes each to train, and from
60,000 to 70,000 machines.

The United States had not provided for such an expansion.
Its July, 1917, plan was the smallest plan that could be adopted
at the time when Italy was victorious and Russia was still fight-
ing. The Senate hearings brought out the fact that it had not
been changed in the early spring of 1918, when the Gei'inan
drive started.

1 The text of Act Creating British Air Ministry is to be founS
in Flying (a monthly published at -29,0 Madison Avenue, New
York City for January, 1918. The text of the first estimates of
British Air Ministry and definition of duties and powers of
officials of the Air Ministry, and the basis of cooperation be-
tween the Air Ministry and the Admiralty and War Office ap-
pear in Flying for May, 1918.

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844

CHAPTER XIX

SOME PROBLEMS IN AEROPLANE CONSTRUCTION

By Capt. V. E. Clark, Chief Aeronautic Engineer, United States Army; Capt. T. F. Dodd, Signal Corps,

United States Army; and D. E. Strahlmann, Engineer, War Department, Office of the Chief Signal

Officer. (Paper presented January 1917 to the Society of Automotive Engineers.)

In this paper we shall advance for discussion, should be entirely defenseless against the attack
with hopes of solution, some important problems of hostile aeroplanes,
connected with the construction of aeroplanes
intended for military uses in the United States.
Many of these problems also apply to aero-
planes built for commercial and sporting pur-
poses. Although the lessons on type develop-
ment that are being learned in the European
war are of immense value to us, many conditions
that we must meet are peculiar to this country.

Military Functions of Aeroplanes

We will first consider the various military
functions (becoming more and more distinct),
as we understand them at present. It must be
borne in mind that other important uses will, in
all likelihood, develop. The aeroplane itself

This and all other service types should carry
one or more machine guns, and the general ar-
rangement of the system should be such as to
permit extensive fields of fire in important direc-
tions.

The useful load, that is, fuel plus the military
load, and the speed range, determine the power
required. A powerplant of about 200 h.p.
would apparently satisfy most economically this
problem, the primary requirements of the
powerplant being reliability and fuel efficiency.

Assuming this, the fuel will weigh between
700 and 800 lbs. The military load will be al-
most 600 lbs. The complete aeroplane, fully
loaded, will weigh over 3,.500 lbs.

This aeroplane would also be adapted for

and its uses in war are so new that it is impos- long-distance transportation of important com-
sible to predict, with any degree of accuracy, munications or officers,
the developments in even a few months. At
present the aeroplane is being used in war for
reconnaissance, fire control, rapid transporta-
tion of important officers or communication, de-
molition of valuable structures by bombing, and
to attack hostile aeroplanes in order to prevent
them from performing these functions.

la — STRATEGICAL-RECONNAISSANCE MACHINES

For this work the fuel capacity should insure
a flight of at least 500 miles without stop. The
average speed during this flight should not be
less than 80 m.p.h. The military load consists
of one pilot, one observer, a sketching outfit, a
camera, a wireless set, and navigating instru-
ments.

The general rule is becoming more and more
firmly established that no military aeroplane

245

lb — TACTICAL-RECONNAISSANCE MACHINES

The fuel capacity of this type should insure a
continuous flight of at least 250 miles at a speed
of not less than 85 m.p.h. The military load
should be about the same as that carried in the
strategical-reconnaissance machine.

A powerplant of about 125 h.p. is desired,
the primary requirement being reliability. The
fuel will weigh about 225 lbs., the aeroplane
loaded somewhat less than 2,400 lbs.

2 — FIELD-ARTILLERY FIRE-CONTROL

The tactical-reconnaissance machine can per-
haps perform this duty, but it appears that the
fire-control machine should be slower, and that
one of its primary requirements should be an

246

TEXTBOOK OF MILITARY AERONAUTICS

extremely good field of vision. The engine
should be of 125 h.p., or perhaps less.

3 LOXG-KAXGER BOMBERS

We here attack a more difficult problem,
owing to the heavy useful load with which we
must cHmb from the starting field.

There will probabh^ be a wide range in sizes
of machines intended for this duty. We will
discuss what we might call an average type at
the present time.

The fuel capacity should permit going out at
least 200 miles and returning safely, starting
with a load of bombs weighing, say, 400 lbs.
The machine should be capable of defending it-
self from hostile aircraft, so that it can operate
independently of escort.

It appears that we need at least 250 h.p. and
that, depending upon the total useful load, 300
h.p., or even 350, would not be too great.

If we assume 300 h.p., the fuel weight will be
at least 900 lbs. and the total military load, in-
cluding bombs, about the same.

This aeroplane will weigh, loaded, between
5,000 and 6,000 lbs.

4 — PURSUIT MACHINES

The function of this type is to attack and
drive off hostile aeroplanes of any of the three
first-mentioned types, preventing them from ac-
complishing their purpose. In fact, the em-
ployment of this type should afford a sort of of-
fensive defense against hostile aircraft of all
descriptions.

"While the types la, lb, 2 and 3 are interested
primarily in objects on the ground, the pursuit
type is occupied solely with events in the air.
This type is at present divided into the one and
two-place subclasses.

a. — The one-place machine carries fuel for
two hours at full speed, about 130 m.p.h. The
pilot is the only occupant. He controls the ma-
chine and operates the machine gun, or guns, of
which there can be from one to four. He usu-
ally aims the gun, in action, by "pointing" his
aeroplane.

All characteristics are sacrificed to reason-
able limits in order to obtain rapid climbing
ability, high speed, rapid climbing ability at

high speed, and the greatest possible dodging
ability, or "handiness."

In the engine, reliability must be sacrificed to
a great extent to obtain low weight per horse-
power, in order that the necessary attributes of
the aeroplane can be obtained. Between 90
and 130 h.p. is desired. At present by far the
greatest percentage of engines in this type of
machine are of the rotary air-cooled type.

b. — The tiico-place machine carries fuel for
three hours at full speed, about 110 m.p.h.
Space is provided for two men, the pilot and the
gun operator. This is, of course, somewhat
larger and less agile than the one-place machine
and, it is believed, is rapidly losing its popu-
larity in favor of the smaller type. The power
required is from 110 to 160 h.p.

5 — oat:rseas reconnaissance

a. — The long-range machine of this type
must carry fuel for six hours at not less than
75 m.p.h. Two men, wireless-transmitting set
and navigating instruments are carried. The
300-h.p. plant used on the bomber should an-
swer for this t\'pe satisfactorily, the greatest
requirements being reliability and fuel effi-
ciency.

b. — The machine used for short-range recon-
naissance and coast-artillery fire-control must
carry fuel for three to four hours at speed of not
less than 75 m.p.h. Two men, navigating in-
struments, wireless and other signaling ajipa-
ratus will be required. The 200-h.i:). engine
used in the land strategical-reconnaissance ma-
chine should answer.

Some Problems in Construction

It is important that engineers work out the
mechanical details of a gi-eat many problems in
construction, among which are the two-propeller
system, the reduction of vibration, the develop-
ment of light engine starters, gasoline supply
systems, devices required for safe landing and
improvements in wing and propeller design.

THE TWO-PROPEEEER SYSTEM

"When an all-around field of fire is necessary,
the best arrangement is to carry the two or three

SOME PROBLEMS IN AEROPLANE CONSTRUCTION

247

operators and the main supply of gasoline in a
central body, and to drive the machine by two
propellers — one at each side of this central body.

By such an arrangement machine guns can be
fired forward, in attack, and to the rear, in re-
treat, with extensive fields of fire in both direc-
tions, above and below, to right and to left.
This attribute is always desirable, and, in some
types, as for instance in the bombers and recon-
naissance machines, is essential.

These propellers can be either tractor screws
or "pushers," The left-hand propeller should
turn clockwise and the right-hand propeller
counter-clockwise. This symmetrical arrange-
ment is a great advantage, in that it permits
equalized torque and gyroscopic efforts when
turning in different directions. In addition, it
makes for safety, because the downward velocity
imparted to the inboard parts of the two slip-
streams that strike the horizontal tail-surfaces
produces an inherent tendency toward nose
heaviness without power and toward tail heavi-
ness with power. We can, therefore, design so
that the line of thrust is considerably above the
center of gravity, compensating for this, and
obtaining another convenient feature.

A fourth great advantage of such a system is
the fact that great power can be transmitted
with good propeller efficiency without demand-
ing excessive diameter and retaining satisfac-
tory structural safety factors. It is highly de-
sirable that the line of thrust of the propeller be
kept below the center of gravity of the aero-
plane, unless the two-propeller arrangement, as
described above, be used; a propeller of large
diameter, with sufficient clearance, necessitates
a high landing gear with its many great disad-
vantages. It appears extremely difficult to
build a propeller of wood, of satisfactory
strength (if the speed of revolution be high),
giving good efficiency, to transmit more than
160 h.p. Peculiarly stringent climatic condi-
tions making for rapid deterioration have in-
creased this difficulty. In fact the tendency to
reduce cylinder diameter and increase crank-
shaft revolution speed is already necessitating a
gear between crankshaft and propeller-shaft in
order to keep the propeller speed below 1,300
r.p.m., which is considered desirable.

A fifth advantage of the two-propeller ar-
rangement is that the total resistance of the air
to progress through it of the complete aeroplane
while flying under power will be diminished
owing to the fact that less total projected area
of bodies will lie in the propeller slip-streams.
The velocity of the air striking objects lying in
the slip stream is, say, 20 per cent, higher than
the velocity of air not in the slip stream. The
resistance varies about as the square of the
velocity. Therefore, all other things being
equal, less power will be required to overcome
the total resistance.

ARRANGEMENTS WITH TWO PROPELLERS

Four different systems for two-propeller in-
stallation have been suggested:

1. Two engines, one on each side, mounted
out on the wings. The fundamental weakness
of this system is that these great masses, re-
moved so far from the center of gravity of the
aeroplane, produce great moments of inertia,
and consequently slow periods of oscillation.
The machine is "logy" and probably not satis-
factory for any but "hydro" purposes, in which
case a "snappy" machine is impossible at best.

2. Two engines mounted in the central body
between pilot and observer, each driving its own
pi'opeller through bevel gears and shafts, or by
other method, the two systems being independ-
ent.

3. One large engine, mounted in the central
body, driving both propellers, one propeller at
each side.

4. Two engines, mounted in the central body,
with a system of clutches connected with the
transmission system in such a manner that either
engine, or both engines, can drive both pro-
pellers, it being possible for the pilot to shift
during flight.

The last system presents many advantages
over the others, but it is entirely possible that
excessive weight and complexity will render it
impracticable. The system, as a whole, must
be reliable.

In the design of any system of transmission
for the two-propeller arrangement, the en-
gineer must bear in mind that the structure of
the wings supporting the propeller and trans-

248

TEXTBOOK OF MILITARY AERONAUTICS

mission is very light and rather flexible, usually
vibrating during flight.

The information at hand indicates that, to
date, no successful aeroplane of the two-pro-
peller type has been developed, but it is urged
that the possible advantages are such as to war-
rant great effort on the part of engineers to-
ward this improvement.

METHODS OF REDUCING VIBRATION

The problem of reducing vibration of the
aeroplane in flight, initiated by the engine, is a
serious one. It is difficult to realize, without
actual experience, the viciousness of this vibra-
tion, especially when the engine is of the eight-
cylinder type, even though it is running nor-
mally. After one experiences this vibration, it
is easy to understand why ignition systems,
gasoline-supply joints, water-cooling systems,
delicate instruments, and even wire terminals
and structural joints of the aeroplane itself, de-
teriorate so rapidly.

The vibration throughout the aeroplane can
of course be reduced by better design of the en-
gine mounting, but we cannot hope to eliminate
it entirely in this manner, if the engine itself is
not of the proper design. We must not, in this
connection, get the idea that the engine is al-
ways operating at the same speed during flight.
We can, for instance, if flying at extremely high
speed, turn the crankshaft over at, say 2,000
r.p.m.; whereas, if our sole object is to remain
in the air without losing altitude, as when spot-
ting for artillery fire, we can use a crankshaft
speed of, say, not more than 1,200 r.p.m. The
vibration at any speed should not be excess-
ive.

STARTING MOTOR FOR ENGINES

The development of light starters is a matter
of immediate importance. For instance, a sea-
plane cfjuipped with two engines, one out on
each wing, would be utterly useless without re-
liable starters. It seems quite probable that
electric starters will be preferable, if the weight
can he reduced sufficiently, and if the danger of
spilling electrolyte be eliminated. It appears
that any engine of over 140 h.p. requires a
starter.

Reliable provision for starting the engine in
extremely cold weather is necessary.

GASOLINE SUPPLY-SYSTEM

To date none of our pilots is anxious to fly
across country with any except gravity feed.

The gasoline supply-systems Figs. 1 and 2,
required by the U. S. Army for twin-engine
seaplanes, is as follows:

The flow of fuel shall be from the main sup-
ply tank in central bodj^ to the gravity service-
tank located at the center of the upper wing;
from gravity service-tank by gravity, along the
lower wing panels, to the small headers at the
carbureters of the two engines, and from the
small headers in each case to the carbureter.

These tanks shall have fuel capacities suf-
ficient for operation at full rated power, as fol-
lows : Main supply tank, 4 hr. 3.5 min. ; gravity
service-tank, 25 min. ; each header to carbureter,
1 min.

The design and material of the gasoline sup-
ply-system throughout shall be such as to ob-
tain extreme lightness as far as consistent with
strength and resistance to corrosion.

MAIN GASOLINE-SUPPLY TANK IN CENTR^VL BODY

This shall be divided by one vertical longitu-
dinal bulkhead and one vertical transverse bulk-

To"k fv Cariurtfr^S

'*(]-Ofi

RFT^P^

Fig. 1 — Gasoline supply system (suction pump) for military
seaplane

head into four gasoline-tight compartments.
Proper swash-baffle plates shall bo installed.
The tank shall be of sturdy construction
throughout.

The main tank shall be of such shape as to

SOME PROBLEMS IN AEROPLANE CONSTRUCTION

249

properly fit the central body. It shall be se-
curely fastened in the structure of the central
body in such a way as to be undisturbed by any
possible motion of the aeroplane. The struc-
ture shall be such that the tank will withstand
an internal pressure of at least 7 lbs. per sq. in.
without leakage of gasoline. The design shall
be such that there will be no ill effects from
drumhead vibration.

Suitable means shall be provided for quickly
and conveniently filling and for completely
draining all four compartments.

Each filling hole shall have a suitable screen
filter, 100 mesh to the inch.

Plugs or caps for filling holes shall be air-
tight and provision shall be made for "safety-
ing" them positively in place. Suitable gaskets
shall be used.

Provision for reducing to a minimum the rate
of leakage due to bullet holes by lining the in-
side of the tank with a special material, is
highly desirable.

Suitable gasoline-supply gage shall be in-
stalled.

There shall be leads from the bottoms of the
four compartments to the upper gravity serv-
ice-tank.

SUPPLY OF GASOLINE FROM MAIN TO GRAVITY-
SERVICE TANK

This shall be by two methods :

First. — Air fan driven pump, so designed as
to maintain proper air pressure in or suction
from the main tank system, and to operate satis-
factorily during flight. An alternative and bet-
ter method will be to install two such fans, each
fan maintaining pressure in any two of the
four compartments of the main tank. When
any one or two of the four compartments of the
main tank leaks (because of bullet hole or
through other cause) , an arrangement by which
pressure or suction can be maintained through
the leads from the tight compartments is highly
desirable.

Second. — A hand air-pressure pump in or at
the side of the pilot's cockpit, which can be used
when not in flight or in an emergency. This
pump shall be located in the cockpit at a point
as high as will permit convenient operation by

the pilot in his seat. It shall be provided with
a suitable air-pressure gage, visible to the pilot.
Its connections with the compartments of the
main tank shall be at a point as high as prac-
ticable to prevent the pump becoming flooded

<^>{>ft

f3F7

Fig. 2 — Gasoline supply system (air pressure) for military sea-
plane

with gasoline. An arrangement by which pres-
sure can be maintained by the hand air-pressure
pump on tight compartments of the main tank
when one or two compartments leak is highly de-
sirable.

CONSTRUCTION OF GRAVITY SERVICE-TANK

This tank shall be of sturdy construction, se-
curely supported in place, and provided with the
proper number of swash-baffle plates. It is
considered desirable to protect this tank. with
light V-shaped armor on the under side.

An automatic ball-float valve shall be pro-
vided to prevent overfilling of this tank. A
suitable overflow pipe out of the top center of
the gravity service-tank shall be provided. The
gravity service-tank shall be of good stream-line
form.

A suitable gage, visible to the pilot in his
seat, shall be in the gravity service-tank. This
gage shall be connected at such a point that it
will register accurately through the range of
normal flight attitudes.

From the gravity service-tank the gasoline
shall be led to a small header at each engine by
leads within or along the lower wing panels.
Between gravity service-tank and each header
shall be two independent, and, as far as prac-
ticable, isolated tube leads. Each of these four

250

TEXTBOOK OF MILITARY AERONAUTICS

leads shall connect with the lower part of the
gravity sen'ice-tank at such a point that the
supply will not be interrupted at any normal
flight attitude.

At the connection of lead to the gravity serv-
ice-tank shall be a suitable wire gauze strainer,
mesh 100 to the inch. Provision shall be made
to prevent the possibility of air pockets in the
gasoline leads from the gravity service-tank.
Provision shall be made for permitting the pilot,
while in his seat, to cut off the gasoline supply,
through all leads, from the gravity service-tank
to the carbureter headers.

HEADERS BETWEEN CARBURETEE AND SERVICE-
TANK

A small cylindrical or stream-line tank or
header shall be installed in the immediate
vicinity of each carbureter. The gasoline shall
pass through this header after coming from the
gravity service-tank.

Its capacity shall be sufficient for one min-
ute's running at full-rated horsepower. The
central portion of this header shall be on a level
with the jets of the carbureter. The axis of the
cylinder shall be vertical.

The cylinder shall be of sufficient length to
give satisfactory head, either when the aero-
plane is in normal attitudes or when it is upside
■down.

Provision shall be made to prevent gasoline
from backing up into the service lead instead of
coming into the carbureter when the engine is
upside down.

Suitable gasoline cutoff shall be installed near
this header in such a position as to be convenient
for operation to a man standing on the ground
or on the wing.

TUBING FOE FUEL LEADS

At every point these shall be of the highest
grade material best suited for the purpose. It
shall he approved by the inspection department.
Flexible tubing shall be ^e-in. No, 2 copper
tubing. Non-flexible leads shall be piping as
approved by the inspection department.

Tubing .shall in all cases be of diameter suffi-
cient to give free and continuous flow under se-

vere vibratory conditions. In the absence of
other instructions the bore shall be %6-in.

All tubing shall be securely fastened in such
a way as to resist wear, vibration, and chafing.
The number of joints and fittings shall be re-
duced to a minimum.

Unions, ells, tees, and fittings, to be S. A. E.
standard, approved by the inspection depart-
ment. The method of connecting all leads shall
be aj^proved by the inspection department. All
fittings shall be readily accessible for inspection,
adjustment, repair, or removal.

It will be seen that it will require consider-
able ingenuity to work out satisfactorily the me-
chanical details of this complicated arrange-
ment. For instance, a satisfactory method of
insuring feed from the compartments of the
main tank, up to the gravity tank, when one or
more of the main compartments are punctured
by shot, is required.

MET^VL CONSTRUCTION FOR AEROPLANES

It is suggested that the field for development
of steel aluminum alloy in the structure of aero-
planes is one offering considerable inducement.
The authors have gone briefly through the lay-
out of an aeroplane in which every strength
member is of metal. In this design it was
found most convenient to use seamless steel tube
at some places, welded tube at others, channel
section at others, I-section and L-section, at
others. At a few points aluminum alloy was
used, at other points pure aluminum, assump-
tion being made that this aluminum was rolled
in such a way as to give it certain desired phj'si-
cal characteristics.

It is suggested that, even with the present
standard method of construction, there is great
room for improvement in the material and
method of heat treatment of the metal fittings
used in conjunction with wood and wire. Es-
pecially where fittings are bent both with and
across the grain, a special alloy appears advis-
able. The same holds for fittings shaped by
die-forging. Chrome vanadium steel, to com-
ply with S. A. E. specifications 6130, and heat
treated in such a way as to render it best in each
case, is suggested. It is believed that the total
weight of an aeroplane can be materially de-

SOME PROBLEMS IN AEROPLANE CONSTRUCTION

251

creased, without sacrifice of strength, and hence
superior performance obtained, by the use of
better steel.

The construction of floats of metal for sea-
planes appears to be a possibility as is also the
use of metal for aeroplane propellers. It is
possible that the entire body might be made of
light pressed steel, or aluminum, with holes to
decrease the weight cut at proper places, and
covered with linen.

ri,EXIBLE PIPING

Satisfactory flexible gasoline lead has not yet
been developed. Such a lead should resist the
action of vibration, should be light in weight and
resist cutting or denting. The method of mak-
ing joints is important. The duct should be
carefully sweated into proper terminal fittings.
Tube ends of fittings should have spiral springs
wound around them for at least 2/4 in., thus pre-
venting sharp bends and disturbing the effects
of vibration. All unions should be ground,
with spherical seats, and threads should be cut
clear and sharp, with all burrs removed. The
inside diameter of tube should not be less than
0.35 in.

A flexible pipe, light in weight, of material
suitable for leading the exhaust away from the
engine would be useful.

MUFFLER REQUIREMENTS

In military service a hostile aeroplane is
usually first discovered by hearing it. A muf-
fler satisfactory as to low weight, flexibility, loss
of power through back pressure, durability
against corrosion, and efficiency as a muffler, is
highly desirable.

SHOCK ABSORBERS FOR LANDING GEAR

Rubber is not satisfactory as a shock absorber
for heavy aeroplanes. Neither is it satisfactory
as a military supply, especially when it is sub-
jected to heat and the direct rays of the sun.
It seems necessary to develop a steel-spring
shock-absorber. The action of this steel spring
must, however, be damped by an oil cylinder.
Without this damping the action is such as to
cause the aeroplane to bound excessively upon
striking the ground.

BRAKES REQUIRED WHEN LANDING

The development of a brake to reduce the run
of the aeroplane after it has touched the ground,
thus permitting it to land in restricted areas,
appears to be a difficult problem. It is a moot
question whether such a brake is desirable when
the simple two-wheel landing gear is used, as its
action has a tendency to throw the aeroplane
over on its nose. Where more than two wheels
are used, however, a brake fitted to the two main
rear outside wheels in such a way that the pilot
can, from his seat, operate either brake, or both
brakes together, would be desirable. Such an
arrangement would permit him not only to stop
his machine quickly, but also to steer it on the
ground to some extent.

FOLDING LANDING GEAR

The development of a landing gear that can
be submerged within the body by the pilot, dur-
ing flight, would materially increase the speed
of the aeroplane by reducing the "parasite" re-
sistance. Such a mechanism should be light in
weight, sturdy and simple.

GASOLINE SUPPLY GAGE

The development of a gage to indicate the
supply of gasoline remaining in the tanks to
the pilot, whose seat can be out of view of the
tanks, is necessary. Such a gage should be
simple and sturdy. The accuracy and re-
liability with which it registers should not be
affected by any change in altitude of the aero-
plane. It should not form a possible source of
leakage. It should be adapted to both the pres-
sure and suction systems of feed.

FIRE SAFETY-DEVICE

Many casualties have occurred because the
aeroplanes have caught fire in the air. While
it has been impossible to determine from the
wreck just what led to the fire, it is quite prob-
able that many of these accidents were due to
back fire into the carbureter that forced burn-
ing gasoline out into the surrounding structure,
or to a leaking gasoline tank. The develop-
ment of a device that will render such an acci-
dent impossible would save many lives.

252

TEXTBOOK OF MILITARY AERONAUTICS

In this connection it should always be a rule
for aeroplane constructors never to have any
electric lead near a gasoline supply or lead.

ALTITUDE ADJUSTMENT FOR A CARBURETER

The development of a device to regulate auto-
matically the mixture for variations in density
of air incident to changes in altitude, would be
valuable.

VIBRATIOX-ABSORBING MATERIAL

The development of a material more suitable
than ordinary felt for padding the points of
support of radiators, and the like, is highly de-
sirable.

VARIABLE RADIATORS

A more suitable method of permitting the
pilot to adjust the amount of cooling done by
the radiator in order to compensate for changes
in temperature of air, or changes in speed
through the air, is necessary. Such arrange-
ment should permit operation by the pilot from
his seat during flight, or, better yet, might be
automatic ; the device being operated as a func-
tion of the temperature of the water. It
should be durable and should act with reliability.

VARIABLE-CAMBER AVING

Great speed range is a desirable attribute of
an aeroplane, as it permits high speed of travel
in the air and yet low speed while landing, which
of course makes for safety if the landing place
be small or rough. Great improvement in the
speed range can be brought about by use of a
variable-camber wing surface, that is to say, if
the section form of the aerofoil could be changed
at will during flight from a shape such as A to
one similar to B, Fig. 3.

tive wind). At small angles of attack, where
the lift coefficient is low, this shape has a rela-
tively high resistance and will consequently re-
quire a gi'eat power to drive it through the air
at speed high enough for the necessary support.

The reverse is true of such a shape as A,
which, though the lift coefficient is poor, has an
appreciably lower resistance or "drag."

If, then, we could utilize the section B for
slow speed, as in making landings, and section
A for high speed, the safe limits of speed be-
tween which the aeroplane could fly would be
extended. The variable-camber would permit
changing the characteristics of the wing to suit
conditions.

Performance curves (Figs. 4 and 5) have

Fig. 3 — Variable forms of aerofoil sections

An aerofoil such as shown in B, has a high
lift coefficient at large angles of attack (the
angle of attack being the angle between the
chord tangent to the lower surface and the rela-

SP£ED MILCS PER HOUR

Fig. 4 — Performance curves for aeroplane with ftxed-camber wing

been worked out for a pursuit machine having a
good aerofoil (ffxed-camber) in common use to-
day ; and a similar series of curves for a machine
with an assumed variable-camber wing. It has
been assumed that otherwise both aeroplanes
are similar. No allowance has been made for
the probable increase in weight of the variable-
camber machine due to the operating mechanism
and structure.

The slow speed of the fixed-cambered wing
aeroplane is 61 m.p.h. This will only permit
landing the aeroplane on an ideal field by a very
skilful pilot.

On the other hand the variable-cambered wing
aeroplane can be flown at a slow speed of 56
m.p.h.

The curves show that with the variable cam-
ber a higher speed, 127 m.p.h., as against 120
for the fixed camber, can be obtained with the

SOME PROBLEMS IN AEROPLANE CONSTRUCTION

253

same power. The same speed might be ob-
tained with less power.

SPEED MILES PER HOWR

Fig. S — Performance curves for aeroplane with variable-camber

wing

// the same high speed were desired the vari-
able-camber wing might have a greater area.
It would then have a slow speed of 46 m.p.h. as
against 61 for the fixed camber (allowing for
increased weight due to added surface), which
would permit its being flown and being landed
in an ordinary field, by the ordinarily skilful
pilot.

It can, therefore, be seen that the invention of
a suitable variable-cambered wing would be a
big step in advance.

APPENDIX

In calculating the values used in plotting the
performance curves. Figs. 4 and 5, the weight
of machine was assumed as 1150 lbs., and the
engine was assumed to develop 140 b.h.p.

The lifting power of a wing is given hy L =
KvA V^, where L is the lift, Kv the lift coefficient
(which varies for different altitudes of the wing
to the relative wind and must be determined by
experiment), A is the area of the wings and V
the air speed.

Similarly the resistance of a wing is expressed
by D = K):A V^, Kx being a variable coefficient
that must be found by experiment.

The speed at which the aeroplane must fly for
any assumed angle of attack can be found from
the lift formula. The lift in all cases, of course,
is assumed to be the weight of the aeroplane.

The resistance of the wings at these speeds
can then be determined and the total resistance

found by adding the parasite resistance, that is,
the resistance of the body, landing gear, etc.

From the total resistance the horsepower re-
quired can be calculated and plotted against
speed. The horsepower available is obtained
by multiplying the efficiency of the propeller by
the brake horsepower delivered by the engine.

I SECTION

Fig. 6 — Rib used in present type of wing construction

The ribs as ordinarily used in the present
type of wing construction are as shown in Fig.
6. The weight of such a rib for a small pur-
suit machine, as assumed in the above calcula-
tions would be less than I/2 lb. The ribs would
be spaced from 12 to 15 in. along the spars. A
wing complete with cover, internal bracing, etc.,
weighs from 0.6 to 0.7 lb.

PKOPELI,ERS WITH VARIABLE-PITCH ANGLE

Improved performance of an aeroplane, espe-
cially as regards radius of action, can be brought
about by means of a propeller whose pitch angle
can be varied by the pilot while in flight. The
liability of failure, the complexity of the mecha-
nism and the weight added, must be weighed
against the gain obtained in the performance.

The gain in efficiency of the variable-pitch
propeller over the fixed-blade type is consider-
able. This increased efficiency makes available
more horsepower for climbing, giving faster
climbing, and permits throttling down to attain
the economical speed, and hence increases the
flight radius and the time in the air with a given
quantity of fuel.

These facts are more clearly brought out by
the approximate curves given in Fig. 7, which
give the horsepower required, and horsepower
available at various speeds for a fast reconnais-
sance type of aeroplane of refined design. The
full lines give the power available for a fixed-
blade propeller; the dotted lines for a variable-
angle blade. It is assumed that the propeller
was designed for maximum efficiency at the high
speed of the aeroplane.

The most evident gain made by using the
variable pitch as observed from the curves is the

254

TEXTBOOK OF MILITARY AERONAUTICS

increased reserve horsepower available for
climbing. This particular assumed aeroplane,
with full load, climbs:

With fixed blade: 650 ft. the first minute.

Fig. 7 — Performance curves for reconnaissance type of aeroplane

With variable-pitch blade: 715 ft. the first
minute.

The increase in the radius of action is very
great, the greatest radius of action being ob-

u»

««0

J'^'

\,^

— --' 1

■J

^^-

to «a 70 so

SPCCO. MILCS PCR HOUR

Fig. 9 — Showing economical speeds of aeroplanes with flxed-
bUde (full lines) and variable-blade (dotted lines) propellers

tained when flying at the economical speed of
the aeroplane. Figure 8 shows the economical
speed in each case.
On one filling of the gasoline tanks the fixed

blade would carry the machine about 690 miles
in 10^ hours. The variable-pitch blade would
carry the same machine a distance of about 10.50
miles in 15i/^ hours. (Were this machine
driven at fuU power it could go but 600 miles
with either propeller. )

These cures, while only approximate, will at
least give some indication as to the value of a
variable-angle propeller, especially where great
distances are to be covered.

The greater efficiency of the variable pitch
would be of value in giving increased climbing

Angle of Attach

ability at high altitudes and the possibility of
reaching greater heights with a given machine.

Another feature possible, of secondary impor-
tance, in a variable-pitch blade is that it can be
rotated to give a large negative angle of attack,
or possibly reversed, when the aeroplane is on
the ground making a landing, thus serving as a
brake and cutting down the distance the ma-
chine rolls on the ground,

APPENDIX

The weight of assumed aeroplane fully loaded
is 2400 lbs. The brake horsepower of engine is
as given in Fig. 11. The fuel capacity is six
hours at full power.

If A denotes the angle that the helix line
makes with the base line. Fig. 9, V the transla-
tional velocity in feet per second and iV the pro-
peller speed in revolutions per second, then the
distance advanced each revolution, neglecting
slip, is (r-^2V) ft., which is the effective pitch
of the propeller.

Suppose the chord XF of the blade section at
any radius V , makes an angle a with the lielix
line. Fig. 9. Angle a is called the angle of at-
tack of the section. As {V-^N) changes
owing to a variation in either V or N, or in both
the blade section will liave a varying angle of
attack, an increase in {V -^ N) decreasing the
angle of attack and vice versa.

SOME PROBLEMS IN AEROPLANE CONSTRUCTION

255

The efficiency of such an element is expressed

c =

tan^

tan {A + G)

where G is the gliding angle, which is a func-
tion of the angle of attack and varies with the

--^

^■■/

/
/

f
1

/
/

■cpeller
Propeller

__w Van

fble-f>ifth

! /

1 /
1 /
t /

t /

2
DISTANCE

4
ADVANCE 0 f

>tR REVOLU

TiOH.FErr

•

Fig. 10

type of section employed. With the usual sec-
tion used in propeller design G is a minimum
when the angle of attack is about 4 deg. It

750 1000 nV> IKK)

REVOLUTIONS PER MINUTE

This can be accomplished by means of a flex-
ible blade whose pitch angles could be changed
a varying amount from the tip of the blade to
the root or hub section. Such a blade is out of
the question in the light of present day practice.
A good approximation to such a blade could be
more simply had by rotating the blade about its
axis perpendicular to the shaft. With the usual
type of section employed the approximation is
good as the value of G does not change greatly
for a degree or so on either side of the best angle
of attack. A mean value for the angle of at-
tack could therefore be found giving practically
the same efficiency as though all the sections
were at the best angle of attack.

Fig. 10 shows curves in which efficiency of a
propeller is plotted against {V-^'N). The
full line gives the efficiency for a fixed blade, the
dotted line the efficiency of the same blade were
the angle of attack kept at approximately 4 deg.
It is assumed that the fixed-blade propeller was
designed for a maximum efficiency at a value of
(r^2V),of about 6 ft.

Propeller Stresses

In connection with the subject of propellers,
it may be of interest to give a brief review of
the variation of stress that occurs in a propeller
blade under an assumed condition of flight.

The blades of a propeller are subject to the
following stresses when an aeroplane is in any
but a straight-line flight:

Fig. 13 — Points of maximum propeller stress

Fig. 11-

-Assumed brake horsepower of Engine Driving variable-
pitch propeller

1. Shear due to aerodynamical forces.

2. Torsion due to the distance between the
would therefore be advantageous from the view- center of gravity of the blade section and the
point of efficiency of the section to keep the point of application of the resultant of the air
angle of attack at 4 deg. throughout the speed reactions.

of the aeroplane. 3. Tension due to centrifugal force.

256

TEXTBOOK OF MILITARY AERONAUTICS

4. Steady bending due to aerodynamic
forces ; torque and thrust imposing a distributed
load on the blade, the hub being the fixed point
of support.

5. Reverse bending due to gjToscopic forces,
which occurs only when the aeroplane has rota-
tion about an axis, as in making a turn or pull-
ing out of a dive. As a matter of fact, an aero-
plane is continually turning to some extent if
the flight be in disturbed air.

Each of these forces produces a maximum
stress of tension and compression in different
parts of the blade, hence the resultant fiber
stress at any point will be equal to the algebraic
sum of the individual stresses at that point.

It is sufficient to calculate the stress at the
points a, b, c, (Fig. 12) along the blade, as these
points will be those of maximum stress.

The shear in any case is small and can be neg-
lected in design. The torsion is also small. In
good designs, when the thrust is great, the point
of application of the air reactions is but little
removed from the axis passing through the cen-
ter of gravity of the section.

The curves of stress given are for a three-
blade propeller of about S^A ft. diameter, 5 ft.
pitch, absorbing 150 h.p. at 1300 r.p.m. The

^ r

JIABIUS IN rccT

5h5»
Pig. IS— Fiber stress In propeller blade at point o (See Fig. 12)

curves are not accurate, as they are intended
merely to give a general idea of the order of
magnitude of the stresses likely to occur in such
a propeller.

The stress caused by centrifugal force is uni-
form over any section of the blade and varies in
intensity at points along the blade, as shown ap-
proximately in Figs. 18, 14 and 15.

Steady bending due to aerodjmamic forces is
caused by torque and thrust. These forces act
along X — X and Y — Y, respectively for any
section, such as shown in Fig. 12. When re-
solved along I — I and II — II they induce bend-
ing moments that cause the fiber stress as shown
in Figs. 13, 14 and 15.

Gyroscopic moments are only induced when
the aeroplane is changing its direction of flight.
In order to estimate the stress set up in the
blades an assumption must be made as to the
angular velocitj^ of the propeller axis; that is,
as to the precession. There is some question
as to the assumption it is reasonable to make in
computing the stresses. The type of aeroplane,
size and disposition of the larger masses, such
as engines, etc., will affect the rate at which a
machine can be turned in flight. In general,
the angular velocity in yaw will not greatly
exceed 0.35 radians per second. It must be re-
membered, however, that a steeply -banked turn
also involves rotation in pitch.

The maximum angular velocity attained in
coming out of a steep dive can be estimated from
the characteristics of the aeroplane and the fac-
tor of safety, which determine the maximum

RAOWS IN FCCT

Fig. 14 — Stress in propeller blade at point 6 (See Fig. 12)

high speed attainable and the radius of curva-
ture of the path along which it is possible to pull
the machine out of its dive safely. A safe value
for the angular velocity in pitch for the usual
type of present-day aeroplanes is about one ra-
dian per second. Loops have been turned in
about 6 seconds, which gives about the value
mentioned of the angular velocity.

A precession of one radian per second at the

SOME PROBLEMS IN AEROPLANE CONSTRUCTION

257

normal speed of the engine should therefore be
assumed in computing the stresses.

The stresses set up by gyroscopic forces are
alternating, changing in sign (tension to com-
pression) twice in each revolution of the propel-
ler about its axis.

RADIUS m FEET

Fig. 15 — Stress in propeller blade at point c (See Fig. 12)

The fiber stress caused by the gyroscopic mo-
ments is given in Figs. 13, 14 and 15. Alge-
braically adding the fiber stress at the three
points chosen gives the approximate value of the
resultant fiber stress at those points, as shown
in the same figures.

It will be noticed that the maximum stresses
occur at some distance out from the hub. To
insure a good wearing blade, which will stand
up under the necessarily hard usage given it
in the field, a factor of safety of not less than
5 is suggested as being the minimum consistent
with requirements when the three principal
stresses are taken into consideration.

Suggestions for Improvements in Design

These suggestions on powerplants are based
on the experience of the First Aero Squadron,
United States Army, in the field.

It is considered extremely poor practice to use
shims under caps of crankpin and crankshaft
bearings.

JNIany American crankcases are not suf-
ficiently rigid in construction. It is believed
that crankcase castings are not designed and
built, in this country, with sufficient care. Some
of the jigs for boring crankshaft and camshaft
bearing seats are not so accurate as desirable.

In some cases it has been found that pistons
are not of uniform weight, and are not carefully
made.

Lack of inter changeability of parts and care-
less workmanship have been great faults in this
country.

OILING SYSTEM

This should be by pressure to all important
bearings, preferably from a gear pump.
Screens should be provided to protect the suc-
tion pumps. For engines that have push-rod
and rocker-arm valve mechanism, means should
be provided to reduce the friction on the ex-
haust-valve rocker-arm bearing, especially if
the valves are more than 1^/4 in. diameter,

IGNITION

All military aeroplanes, except possibly the
pursuit type, should have two complete and in-
dependent ignition systems.

Engines larger than 140 h.p. should have a
booster system for starting on battery spark, if
a starter is not provided.

It is believed that our magnetos would have
much longer life if a more suitable shock-ab-
sorbing device between the driving gear and
the magneto shaft were provided, A magneto
mounting should be machined so that the mag-
neto shaft will be exactly in line with its driving
shaft; dowel pins and dowel-pin holes to pre-
serve this alignment should be provided. No
shims should be used here. We have had con-
siderable trouble because of non-uniform and
warped carbon brushes.

FUEL SUPPLY

Carbureters should be located in such a way
that oil, water and impurities cannot enter them.
They should be supported from the engine and
not from the frame work of the aeroplane.
They should be supported independently of the
intake manifolds, if practicable.

Gaskets for connections in intake manifolds
should be as thin as practicable. Manifolds
built of copper, brazed, or of steel, welded, are
considered preferable to cast manifolds. Steel
is considered preferable, but should, of course,
be heat treated after welding.

258

TEXTBOOK OF MILITARY AERONAUTICS

It is urged that more study and care should
be put into the design relating to shape and fin-
ish of the interior of intake manifolds and pas-
sages. It is believed, in this connection, that
much greater efficiency can be obtained by at-
tention to fluid flow.

COOLING SYSTEM

Radiators should preferably be placed at the
leading edge of the upper wing, the header be-
ing shaped so as to form part of this leading
edge. If it is necessary to place the radiator

between the engine and the propeller, the radia-
tor should be circular. The radiator should be
provided with a sufficient number of points of
support to prevent deformation of the shell ow-
ing to shocks on landing.

Care should be taken with the alignment of
tubes at the connections in the water-circulating
system. A ring reinforcement might be welded
to a flanged end of the thin tubing and the face
machined so as to make a good fit to the cylin-
der jacket. It is considered bad practice to ex-
pand thin tubing.

Memoranda:

CHAPTER XX

METHODS OF MEASURING AIRCRAFT PERFORMANCES

By Capt. H. T. TizAKi), R.F.C.

Aeroplane Testing

The accurate testing of aeroplanes is one of
the many branches of aeronautics which have
been greatly developed during the war, and es-
pecially during the last year. For some
months after the war began a climb of 3,000 to
5,000 ft. by aneroid and a run over a speed
course was considered (juite a sufficient test of a
new aeroplane; now we all realize that for mili-
tary reasons certainly, and probably for com-
mercial reasons in the future, it is the perform-
ance of a machine at far greater heights with
which we are mainly concerned. In this paper
I propose to give a short general account of
some of the methods of testing now in use at the
Testing Squadron of the Royal Flying Corps,
and to indicate the way in which results of actual
tests may be reduced, so as to represent as ac-
curately as possible the performance of a ma-
chine independently of abnormal weather con-
ditions, and of the time of the year. For ob-
vious reasons full details of the tests and meth-
ods employed cannot yet be given. So far as
England is concerned, I believe that the general
principles of what may be called the scientific
testing of aeroplanes were first laid down at the
Royal Aircraft Factory, Our methods of re-
duction were based on theirs to a considerable
extent, with modifications that were agreed
upon between us; thejj^ have been still further
modified since, and recently a joint discussion
of the points at issue has led to the naval and
military tests being coordinated, so that all of-
ficial tests are now reduced to the same stand-
ard. It should be emphasized that once the
methods are thought out scientific testing does
not really demand anv high degree of scientific
knowledge ; in the end the acciu-acy of the results
really depends upon the flyer, who must be pre-

pared to exercise a care and patience unneces-
sary in ordinary flying. Get careful flyers
whose judgment and reliabilitj'^ you can trust
and your task is comparatively easy; get care-
less flyers and it is impossible.

At the outset it may be useful to point out by
an example the nature of the problems that drise
in aeroplane testing. Suppose that it is desired
to find out which of two wing sections is most
suitable for a given aeroplane. The aeroplane
is tested with one set of wings, which are then
replaced by the other set and the tests repeated
some days later. The results might be ex-
pressed thus:

A Wings.

Speed at 10,000

Rate of climb at

10,000 ft 250 ft

90 m.p.h..

B Wings.
93 m.p.h.

a minute. 300 ft. a minute.

259

Now, the intelligent designer knows, or soon
will know, that, firstly, an aneroid may indicate
extremely misleading "heights": and, secondly,
that even if the actual height above the ground
is the same in the two tests, the actual conditions
of atmospheric pressure and temperature may
have been very different on the two days. He
will therefore say. What does that 10,000 mean?
Do you mean that yoiu* aneroid read 10,000 ft.,
or do you mean 10,000 ft. above the spot you
started from, or 10,000 ft. above sea-level? If
he proceeds to think a trifle further he will say,
What was the density of the atmosphere at your
10,000 ft.; was it the same in the two tests? If
not, the results do not convey much. There he
will touch the keynote of the whole problem, for
it is on the density of the atmosphere that the
whole performance of an aeroplane depends;
the power of the engine and the efficiency of the
machine depends essentially on the density, the
resistance to the motion of the machine through

260

TEXTBOOK OF MILITARY AERONAUTICS

the air is proportional to the density, and so
finally is the lift on the wings. None of these
properties are proportional solely to the pres-
sure of the atmosphere, but to the density — that
is, the weight of air actually present in unit vol-
ume. It follows that it is essential when com-
paring the performances of machines to com-
pare them as far as possible under the same
conditions of atmospheric dcnmti/, not as is
loosely done at the same height above the earth,
since the density of the atmos])here at the same
height above the earth may vary considerably on
different days, and on the same day at different
places.

-zoooo

I6O0O

ISOOO

fiooo

VartJtl

Fig. I.

ions of lemaerature uiilh Heiifht.

\ \''*

V-.

\ 1

v^,_

Jo So la

TEMPERATURE

At the same time, in expressing the final re-
.sults, this principle may be carried too far.
Thus, if the speed of a machine were exjiressed
as 40 meters a second at a density of 0.8 kilogs.
per cubic meter, the statement, though it may be
strictly and scientifically accm-ate, will convey
nothing to 99 per cent, of those directly con-
cerned with the results of the test. The result
is rendered intelligible and, indeed, useful by
the form, "90 m.p.h. at 10,000 ft.," or whatever
it is. With this form of statement, in order
that all the statements of results may be con-
sistent and comparative, we must be careful to
mean by "10,000 ft." a certain definite density
— in fact, the average density of the atmosphere
at a height of 10,000 ft. above mean sea-level.
This is what the problem of "reduction" of tests
Imils down to: what is the relation between at-
mospheric density and height above sea-level?

This knowledge is obtained from meteorological
observations. We have collected all the avail-
able data, mostly unpublished, with results
shown in the following table: —

Table 1. — Mean Atmospheric Pressure, Temperature
and Density at various Heights above Sea-level.

Mean temp.

Mean

Height

Height in

Mean

in absolute

density in

equivalent

pressure m

degrees

kgm. per

Kiloms.

feet.

millibars.

Centigrade.

cubie meter

1,014

282

1.253

3,280

900

278

1.128

6,560

795

273

1.014

9,840

699

268

0.909

13,120

615

262

0.818

16,400

568

255

0.735

19,680

469

248

0.658

22,960

407

241

0.589

These are the mean results of a long series of
actual observations made mainly by Dr. J. S.
Dines. It is convenient to choose some density
as standard, call it unity, and refer to all other
densities as fractions or percentages of this
"standard density." We have taken, in con-
formity with the R.A.F., the density of dry
air at 760 mm. pressure and 16° C. as our stand-
ard density; it is 1.221 kilog. per cubic meter.
The reason this standard has been taken is that
the air speed indicators in use are so constructed
as to read correctly at this density, assuring the
law : p = VipY^, where V is the air s])eed. p the
pressure oI)tained, i> the standard density.

In some ways it would doubtless be more con-
venient to take the average density at sea-level
as the standard density, but it does not really
matter what you take so long as you make your
units quite clear. Translated into feet, and
fraction of the standard density, the above table
becomes : —

Table II.

Height
in feet.

Percentage

of standarc

density.

Height
in feet.

Percentage
of standard Height
density. in feel.

Percentage

of standard

density.

102.6

7.000

81.9

15,000

63.0

1,000

99.4

8,000

79.2

16.000

61.1

2.000

96.3

9,000

76.5

1 16.500

60.1

3,000

93.2

tl 0,000

74.0

17.000

.59.1

4.000

90.3

11.000

71.7

18.000

.57.1

5.000

87.4

12,000

69.5

19.000

.55.2

6,000

84.6

1 13,000

67.3

20.000

53.3

t6,500

83.3

14,000

65.2

METHODS OF MEASURIXG AIRCRAFT PERFORMANCES

261

Let us briefly consider what these figures
mean. For example, we say that the density
at 10,000 ft. is 74 per cent, of our standard
density, but it is not meant that at 10,000
ft. above mean sea level the atmospheric
density will always be 74 per cent, of the stand-
ard density. Unfortunately for aeroplane
tests this is far from true. The atmospheric
density at any particular height may vary con-
siderably from season to season, from day to
day, and even from hour to hour; what we do
mean is that if the density at 10,000 ft. could be
measured everj^ day, then the average of the re-
sults would be, as closely as we can tell at pres-
ent, 74 per cent, of the standard density.

The above table may therefore be taken to
represent the conditions prevailing in a "nor-
mal" or "standard" atmosphere, and we en-
deavor, in order to obtain a strict basis of
comparison, to reduce all observed aeroplane
performances to this standard atmosphere, i.e.,
to express the final results as the performance
which may be expected of the aeroplane on a
day on which the atmospheric density at every
point is equal to the average density at the point.
Some days the aeroplane may put up a better
performance, some days a worse, but on the
average, if the engine power and other charac-
teristics of the aeroplane remain the same, its
performance will be that given.

It must be remembered that a standard at-
mosphere is a very abnormal occurrence; be-
sides changes in density there may occur up-
and-down air currents which exaggerate or
diminish the performance of an aeroplane, and
which must be taken carefully into account.
They show themselves in an otherMise imac-
countable increase or decrease in rate of climb
or in full speed flj'ing level at a particular
lieight.

We now pass to the actual tests, beginning
with a description of the observations which
have to be made and thereafter to the instru-
ments necessary. The tests resolve themselves
mainly into (a) A climbing test at the maxi-
mum rate of climb for the machine, {h) Speed
tests at various heights from the "ground" or
some other agreed low level upwards.

Experience agrees with theory in showing

that the best climb is obtained by keeping that
which is frecjuently called the air speed of an
aeroplane, viz., the indications of the ordinary
air speed indicator, nearly constant whatever
the height — in other words, pV is kept con-
stant. We can look at this in this way. There
is a limiting height for every aeroplane above
which it cannot climb; at this limiting height,
called the ceiling of the machine, there is only
one speed at which the aeroplane will fly level,
at any other air speed higher or lower it will
descend. Suppose this speed be 55 m.p.h. on
the air speed indicator. Then the best rate of
climb from the ground is obtained by keeping
the speed of the machine to a steady indicated
55 m.p.h. Fortunately a variation in the speed
does not make very much diff'erence to the rate
of climb; for instance, a B.E.2c with a maxi-
mum rate of climb at 53 m.p.h. climbs just as
fast up, say, 5,000 ft. at about 58 m.p.h. This
is fortunate as it requires considerable concen-
tration to keep climbing at a steady air speed,
especially with a light scout machine; if the air
is at all "bumpy" it is impossible. At great
heights the air is usually very steady, and it is
much easier to keep to one air speed. It is
often difficult to judge the best climbing speed
of a new machine; flyers differ very much on
this point, as on most. The Testing Squadron,
therefore, introduced some time ago a rate of
climb indicator intended to show the pilot when
he is climbing at the maximum rate. It con-
sists of a thermos flask, communicating with the
outer air through a thermometer tube leak. A
liquid pressure gage of small bore indicates the
difference of pressure between the inside and
outside of the vessel. Now, when climbing, the
atmospheric pressure is diminishing steadily;
the pressvu'e inside the thermos flask tends
therefore to become greater than the outside
atmospheric pressure. It goes on increasing
until air is being forced out through the ther-
mometer tubing at such a rate that the rate of
change of pressure inside the flask is equal to
the rate of change of atmospheric pressure due
to climbing. When chmbing at a maximum
rate, therefore, the pressure inside the thermos
flask is a maximum. The pilot therefore varies
his air speed until the liquid in the gage is as

262

TEXTBOOK OF MILITARY AERONAUTICS

high as possible, and this is the best climbing
speed I'or the machine.

What observations during the test are neces-
sary in order that the results may be reduced
to the standard atmosphere? Firstly, we want
the time from the start read at intervals, and the
height reached noted at the same time. Here
we encounter a difficulty at once, for there is no
instrument which records height with accuracy.
The aneroid is an old friend now of aeronauts
as well as of mountaineers, but although it has

riCuKE 2

X^OAr

^•-■86; g S^*.oseOPf

often been tentatively exposed, it is doubtful
whether 1 i)er cent, of those who use it daily
realize how extraordinarily rare it is that it ever
does what it is supposed to do, that is, indicate
the correct height above the ground, or starting
jjlace. The faults of the aeroplane aneroid are
partly unavoidable and partly due to those who
first laid down the conditions of its manufac-
ture. An aneroid is an instrument which in the
first place measures only the pressure of the
surrounding air. Now if pi and po are the
pressure at two points in the atmosphere, the
difference of height between these points is
given very closely by the relation, h — <^ log,
'"/p2 where ^ is the average temperature, ex-
pressed in "absolute" degrees, of the air between
the two ])oints. It is obvious that if we wish
to graduate an aneroid in feet we must choose
arbitrarily sonie value for *. The temperature
that was originally chosen for aero|)lnne ane-
roids was .50'' F. or 10'' C. An aneroid, as now
graduated, will therefore only read the correct
height in feet if the atmosphere has a uniform
temperature of .50° F. from the ground up-

wards, and it will be the more inaccurate the
greater the average temperature between the
ground and the height reached differs from .50^
F. Unfortunately 50° F. is nuich too high an
average temperature ; to take an extreme exam-
ple, it is only on the hottest days in summer, and
even then very rarely, that the average tempera-
ture between the ground and 20,000 ft. will be
as high as 50° F. On these very rare occasions
an aneroid will read approximately correctly at
high altitudes; otherwise it will always read too
high. In winter it may read on cold days 2,000
ft. too high at 16,000 ft., i.e., it will indicate a
height of 16,000 ft. when the real height is only
14,000 ft. It is always necessary, therefore, to
"correct" the aneroid readings for temperature.
The equation

Tx _ 273 + t ,

gives us the necessary correction. Here H is
the true difference in height between any two
points, t the average temperature in degrees
Centigrade between the points, and h the differ-
ence in height indicated by aneroid. It is con-
venient to draw a curve showing the necessary
correction factors at different temperatures,
some of which are given below: —

Tabi.e III. — .Aneroid Correction Factors.

Temperature Correction Temperature Correction

° F. factor. " F. factor.

70 1.04.0 10 0.9522

50 1.000 —10 0.833
30 0.961

For example if a climb is made through 1,000
ft. by aneroid and the average temperature is
10° v., the actual distance in feet is only
1,000 X 0.922 = 922 ft. The above equation
is probably quite accurate enough for small dif-
ferences of height — up to 1,000 ft. say — and ap-
j)roximately so for bigger differences. The
magnitude of the correction which may be nec-
essary shows how important it is that observa-
tions of temperature should be made during
every test. P"'or this purpose a special tlier-
mometer is attached to a strut of the machine,
well away from the fuselage, and so clear of any
warm air which may come from the engine.

METHODS OF MEASURING AIRCRAFT PERFORMANCES

263

The p^'rench, I believe, do not measure tempera-
ture, but note the ground temperature at the
start of a test, and assume a uniform fall of
temperature with height. This, undoubtedly,
may lead to serious errors. The change of tem-
perature with height is usually very irregular,
and only becomes fairlj^ regular at heights well
above 10,000 ft.

The aneroid being what it is, one soon comes
to the conclusion that the only way to make use
of it in aeroplane tests is to treat it purely as a
pressure instrument. For this reason it is best
to do away with the zero adjustment for all
test purposes and lock the instrument so that
the zero point on the height scale corresponds
to the standard atmospheric pressure of 29.9 ins.
or 760 mm. of mercury. Every other height
then corresponds to a definite pressure; for in-
stance, the locked aneroid reads 5,000 ft. when
the atmospheric pressure is 24.88 ins., and
10,000 ft. when it is 20.70 ins., and so on, If
the temperature is noted at the same time as the
aneroid reading, we then know both the atmos-
pheric pressure and temperature at the point,
and hence the density can be calculated, or,
more conveniently, read off curves drawn for
the purpose. The observations necessary
(after noting the gross aeroplane weight and
net or useful weight carried) are therefore: (i)
Aneroid height every 1,000 ft.; (ii) time which
has elapsed from the start of the climb; and (iii)
temperature. To these should be added also
(iv) the air speed and (v) engine revolutions at
frequent intervals. The observed times are
then plotted on squared pa])er against the ane-
roid heights and a curve drawn through them.
From this curve the rate of climb at any part
(also in aneroid feet) can be obtained by meas-
uring tlie tangent to the curve at the point.
This is done for every 1,000 ft. by aneroid.
The true rate of climb is then obtained by mul-
tiplying the aneroid rate by the correction fac-
tor corresponding to the observed temperature.
These true rates are then plotted afresh against
standard heights, and from this curve we can
obtain the rate of climl) corresponding to the
standard heights, 1,000. 2,000, 3,000, etc.
Knowing the change of rate of climb with
height, the time to any required height is best

obtained by graphical integration. The table
below gives the results of an actual test.

At least two climbing tests of every new ma-
chine are carried out up to 16,000 ft. or over by
aneroid. If time permits three or more tests
are made. The final results given are the aver-
age of the tests and represent as closely as pos-
sible the performance on a standard day, with
temperature effects, up and down currents and
other errors eliminated.

If we i^roduce the rate of climb curve up-
wards it cuts the height axis at a point at which
the rate of climb would be zero, and therefore
the limit of climb reached. This is the "ceiling"
of the machine.

SPEEDS

His 16,000 ft., or whatever it is, reached, the
flyer's next duty is to measure the speed flying
level by air speed indicator at regular intervals
of heiglit (generally every 2,000 ft.) from the
highest point downwards. To do this, he re-
quires a sensitive instrument which will tell him
when he is flying level. The aneroid is quite
useless for this purpose, and a "statoscope" is
used. The principle of this instrument is really
the same as that of a climb meter. It consists
of a thermos flask connected to a small glass
gage, slightly cun^ed, but placed about hori-
zontally (see Fig. 2). In this gage is a small
drop of liquid, and at either end are two glass
traps which prevent the liquid from escaping
either into the outside air or into the thermos
flask. As the machine ascends and the atmos-
pheric pressure being smaller, and the pressure
in the flask being higher than the external pres-
sure, the liquid is pushed up to the right hand
trap, where it breaks, allowing the air to escape.
On descending the reverse happens; the liquid
travels to the left, breaks, and air enters the
flask. When flying truly level the drop re-
mains stationary, moving neither up nor down.
The instrument is made bv the British Wright
Co.

The flyer or the observer notes the maximum
speed by the air speed indicator — i.e., the speed
at full engine throttle. At one or more heights,
also, he observes the speeds at various positions
of the throttle down to the minimum speed

264

TEXTBOOK OF MILITARY AERONAUTICS

wliich will keep the machine flying at the height
in question. The petrol consumption and the
engine revolutions are noted at the same time,
as well, of course, as the aneroid height and
temperature. Accurate observation of speeds
needs very careful flying — in fact much more so
than in climbing tests. If the air is at all
bumpy observations are necessarily subject to
much greater error, since the machine is always
accelerating and decelerating. The best way to
carry out the test seems to be as follows. The
machine is flown first just down hill and then
just up hill, and the air speeds noted. This

Ficunc 3

will ^'e a small range between which the real
level speed must lie. The flyer must then keep
the speed as steadily as possible on a reading
midway between these limits, and watch the
statoscope with his other eye. If it shows
steady movement, one way or the other, the air
speed must be altered accordingly by 1 m.p.h.
In this way it is always possible at heights where
the air is steady to obtain the reading correct at
any rate to 1 m.p.h., even with light machines,
provided always sufficient ])atience is exercised.
The r.p.m. at this speed are then noted.

One difficulty, however, cannot be avoided.
If at any height there is a steady up or down
air current, then though the air may appear
calm, i.e., there may be no "bumps," the air
speed indicator reading may be wrong, since to
keep the machine IcxtI in an up current it is
necessary to fly slightly down hill relatively to
the air. Such unavoidable errors are. however,
eliminated to a large extent by the metliod of
taking speeds every 2,000 ft., and finally aver-
aging the results.

We must now consider how the true speed of
the aeroplane is deduced from the reading of
the air speed indicator. It is well known that

an air speed indicator reads too low at great
heights — for example, if it reads 70 m.p.h. at
8,000 ft. the real speed of the machine through
the air is nearer 80 m.p.h. The reason for this
is that the indicator, like the aneroid, is only a
pressure gage — a sensitive pressure gage, in
fact, which registers the difl'erence of pressure
between the air in a tube with its open end point-
ing forward along the lines of flight of tlie ma-
cliine, and the real pressure (the static ])ressure)
of the external air. This difference of pressure
is as nearly as we can judge by experiment —
Vi p V^ (where p is the density of the air and V
the speed of the machine) , provided that the
open end of the tube is well clear of Avings,
fuselage, etc., and so is not affected by eddies
and other disturbances. Now, assuming this
law, air speed indicators are graduated to read
correctly, as I have said above, at a density of
1.221 kgm. per cubic meter, which we have
taken as our standard density and called
"unity." It corresponds on an average to a
height of about 800 feet above sea level.

Then suppose the real air sj^eed of an aero-
plane at a height of "h" feet is V m.p.h., and the
indicated air speed is 70 m.p.h., this means that
the excess pressure in the tube due to the speed
is proportional to 1 X 70^,

or P X F'^ = 1 X 70^

where p is the density at the height in question,
expressed as a fraction of the standard density.
To correct the observed speed, we therefore
divide the reading by the square root of the
density. Thus, observation of the maximum
speed of an aeroplane at a height of 8,000 ft. by
the locked aneroid gave 80 m.p.h. on the indi-
cator, the temperature })eing 31° Fahr. From
the cun'e we find that the density corresponding
to 8.000 ft. and 31" is 0.8.'> of standard density.
The corrected air speed is therefore:

V .8.)

86.7 m.p.h.

This "corrected" air speed will only be true
if the above law holds, that is to say, if there
are no disturbances due to the jjressure head
being in close proximity to struts or wings. It
is always necessary to find out the magnitude

METHODS OF MEASURING AIRCRAFT PERFORMANCES

265

of this possible error, that is, to calculate the
air speed meter, and the only waj' to do this is
to measure a real air speed at some reasonable
altitude for easy observation of the aeroplane
by actual timed observations from the ground,
and from these timed results check those de-
duced from the air speed indicator readings.
This calibration is the most important and diffi-
cult test of all, since on the accuracy of the re-
sults depends the accuracy of all the other speed
measurements. It can either be done by speed
trials over a speed course close to the ground,
or when the aeroplane is flying at a considerable
height above the ground. In the Testing
Squadron we have always attached much more
importance to the latter method, mainly be-
cause the conditions approximate more to the
conditions of the ordinary air speed measure-
ments at different heights, and because the
weather conditions are much steadier and the
flyer can devote more attention to flying the
machine at a constant air speed than he can
when very close to the ground.

One method is to use two camera obscuras,
one of which points vertically upwards and the
other is set up sloping towards the vertical
camera. At one important testing center the
cameras are a mile apart, and the angle of the
sloping camera is 45°. By this arrangement, if
an aeroplane is directly over the vertical camera
it will be seen in the field of the sloping camera
if its height is anywhere between 1,500 and
15,000 feet, although at very great heights it
would be too indistinct for measurements except
on a very clear day. The height the tests are
usually carried out is 4,000 ft. to 0,000 ft.

The aeroplane is flown as nearly as possible
directly over the vertical camera and in a direc-
tion approximately at right angles to the line
joining the two cameras. The pilot flies in as
straight a line and at as constant an air speed
as he can. Observers in the two cameras dot in
the position of the aeroplane every second. A
line is drawn on the tables of each camera point-
ing directly towards the other camera, so that
if the image of the aeroplane is seen to cross
the lines in the one camera it crosses the line
in the other simultaneously. From these ob-
servations it is possible to calculate the height

of the aeroplane with considerable accuracy; the
error can be brought down to less than 1 part
in a 1,000 with care. Knowing the height, we
can then calculate the speed over the ground
of the aeroplane by measuring the average dis-
tance on the paper passed over per second by
the image in the vertical camera. If j? inches
is this distance, and / the focal length of the
lens, the ground speed is a? X h/f feet per sec-
ond.

It is necessary to know also the speed and
direction of the wind at the height of the test.
For this purpose the pilot or his observer fires
a smoke puff' slightly upwards when over the
cameras, and the observer in the vertical camera
dots in its trail every second. The height of
the smoke puff is assumed to be the same as that
of the aeroplane — it probably does not differ
from this enough to introduce any appreciable
error in the results. The true speed through
the air is then found graphically as shown in
Fig. 4. Here the length AB represents the
ground speed of the aeroplane as measured in
the camera and CB represents on the same scale
the velocity and direction of the wind. The
length AC represents, also on the same scale,
the true air speed of the machine.

The tests are done in any direction relative
to the wind, and generally at three air speeds,
four runs being made at each air speed.

The advantages of this method are:

(1) Being well above the earth the pilot can
devote his whole attention to the test.

(2) Within reasonable limits any height can
be chosen, so that it is generally possible to find
a height at which the wind is steady.

(3) It does not matter if the pilot does not
fly along a level path so long as he does so ap-
proximately. What is more important is that
he should fly at a constant air speed.

(4) It is not necessary that there should be
any communication between the two cameras,
although it is convenient. The two tracks are
made quite independently, and synchronized
afterwards from the knowledge that the image
must have passed over the center line simul-
taneously in the two cameras.

The main disadvantage is that somewhat
elaborate apparatus is necessary, but this is of

266

TEXTBOOK OF MILITARY AERONAUTICS

not much importance in a permanent testing
station.

There are often jjcriods in war time, however,
when an aeroplane has to be tested quickly, and
low cloud layers and other causes prevent the
camera test from being carried out. It is then
necessary' to rely on measurements of speeds
near the ground for the calibration of the air
speed indicator. In this method the aeroplane
is flown about 10 ft. off the ground, and is timed
over a measured run. There are two observ-
ers, one at each end of the course: when the
aeroplane passes the starting point the observer

ocfc^lowfc 0" H<» ground

Thi^tto" AC 'tyrmnft rtic r<ol «^<d oj ftit
Otro^owt H\rouqK iKc Olf.

sends a signal and starts his stop-watch simul-
taneously; the second observer starts his stop-
watch directly he hears the signal, and in his
turn sends a signal and stoj)s his watch when
the aerojjlanc passes the finishing point. By
this double timing, errors due to the so-called
"reaction time" of the observers are practically
eliminated, for the observer at the end of the
course tends to start his watch late, while the
first observer Hto])H his late. The mean of the
two observations gives the real time. Four
runs, two each up and down the course, are done
at each air speed, the pilot or his observer noting
carefully the average air s])eed during the run.
Observations of the atmos|)heric ])ressure and
temperature from which the density can be ob-
tained are also taken. The average strength
and direction of t))e wind during each trial are
noted frf)m a small direct reading (or record-
ing) anemometer and the speed corrected in the
same waj* as in the camera tests. If there is a

strong cross wind the aeroplane may have to be
pointed at a considerable angle to the course,
and this makes the test a very difficult one to
carry out well. Generally speaking, it is only
reliable when the wind is quite light, not more,
at any rate, than 10 m.p.h. Even this is too
strong if it is a cross wind.

A further difficulty is that at high speeds, over
100 m.p.h., an aeroplane may take quite a con-
siderable time to accelerate up to a steady speed,
and so it must fly level for a long distance each
end before reaching the actual course. At the
testing station previously alluded to the course
is a mile long, and there is a clear half-mile or
more at each end, but it is doubtful whether
even this distance is enough for the machine to
attain steady speed before the starting ])oint.
Finally, the flyer of a single-seater is generally
too busy watching tlie ground to do more than
glance at his air speed indicator more than a few
times during the run. Doubtless it woifld be
better in such a case to use some form of record-
ing air speed instrument, although then other
difficulties would arise.

Having got the true air speed from camera or
speed course tests, and knowing the density at
the height at which the test was carried out. we
obtain what the air speed indicator should have
read hy multiplying the measured air speed by
the square root of the density. By comparing
this with the actual reading of the indicator we
obtain the necessary correction. The whole
j)rocedure may be shown best by a table giving
part of the results of a camera test made at the
beginning of the year.

A summary of the complete speed tests may
now be given. Firstly, the air speed and en-
gine revolutions are noted flying level at full
throttle every 2,000 feet approximately by ane-
roid. From the aneroid reading and temjjera-
ture observation at each height the density is
obtained. The reading of the air s])eed indi-
cator is then first corrected for instrumental
errors by adding or subtracting the correction
found by calibration tests over the cameras or
speed course. This number is then again cor-
rected for height by dividing by the square root
of the density. Tiie result should give the true
air speed, subject, of course, to errors of obser-

METHODS OF MEASURING AIRCRAFT PERFORMANCES

267

vation. The numbers so obtained are plotted
against the "standard" heights, i.e., the average
height in feet corresponding to the density dur-
ing the test. A smooth curve is then drawn
through the points and the air speeds at stand-
ard heights of 3,000, 0,500, 10,000, 13.000 and
10,500 read oft* the curve. These heights are
chosen because they correspond closely with 1,

-Figure S —

2, 3, etc., kilometers. The indicated engine
revolutions are also plotted against the standard
heights, because these observations form a check
on the reliability of the results; also the ratio of
speed to engine revolutions at different heights
may give valuable information with regard to
the propeller.

Table VI gi\es complete results of one of our
tests of air speed at heights. The table refers
to the same machine as Table V, which gives the
results of calibration tests of the air speed indi-
cator. Fig. 5 shows the smooth curve drawn
from the calculated data, the actual air speeds
calculated from the observations being shown
by crosses, while the observed engine revolutions
at the same heights are marked in by dots. Fig.
6 gives another example, where the observations
were very good; the air speeds and r.p.m. lie
very closely on a smooth curve except at one
point (about 10,000 ft.), where they were prob-
ably affected by a downward current of air.

In a brief pa])er it is impossible to do more
than explain the more important of the "per-
formance" tests of aeroplanes, considered solely
as flying machines. For military purposes a
number of tests are necessary, some of which
cannot easily be reduced to figures. Nor can it
be supposed for an instant that the methods
outlined here are final; aeroplane testing, Uke

all other work connected with aeroplanes, is only
in its infancy; and as time goes on, and knowl-
edge accumulates, better methods and instru-
ments will be evolved. There are some who lay
considerable emphasis on the necessity of every
test instrument being self-recording, and al-
though this scheme appears at first sight Uto-
pian and would relieve the pilot of a single-
seater of considerable trouble, there are many
objections to it when considered in detail, not
the least of which is the difficulty of getting new
and elaborate instruments made at a time when
all manufacturers are fully engaged on other im-
portant work. When an observer can be taken
I would personally place much more reliance on
direct observations at the present time, and one
great advantage of direct observation is that the
results are there, and no time is lost through the
failure of a recording instrument to record, a
circumstance which is not unknown in practice.
So far as we use recording instruments we use
them only as a check on direct observations, al-
though we shall probably soon adopt I'ccording
air speed indicators for the calibration tests,
liut whether recording or direct reading instru-
ments are used, it is, as I said before, the flyer

on whom the accuracy of the tests depends. I
feel that too great stress cannot be laid on tliis;
he is the man who does most of the experiments,
and like all experimenters in every branch of
science, he requires training and a great deal of
practice. Although the methods themselves
may l)e greatly changed, this much may perhaps
be claimed, that the general principles on which
they are founded are sound, and will only be
altered in detail. The importance of the work
can hardly be exaggerated; model experiments
are notoriously subject to scale and other cor-

268

TEXTBOOK OF MILITARY AEROXAUTICS

rections, w

hich if not carefully scrutinized maj'

TABLE V

be very
full sea

' in

sleading,
eork that

and it is

only by accurate
ope to maintain a

Calibration Test of Air Speed Indicator No. . .

le y

we can h

On.

Machine Date, 24/12/16

steady

improvement in the efficiency

of aero-

Measured Corrected

Observed

planes.

Measured

wind si)eed true ( = V)

Aneroid

Run No.

ground s])eed and direction airspeed

height

TABLE IV

59.1 m.p.h.

31.0 m.p.h. 1G1.5 89.3

5,100

M
ne. .

achinc

2
3

123.4 "
62.0 "

28.6 " 5.5 93.7
32.3 " 168.5 93.8

5,100

Eng

5,050

Date 27/12/16

134.7 "

32.3 " 21.0 95.6

5,000

Height in
Aneroid ft.

0
1,000
2,000

Observed Percentage of
temp. standard density

36° Fahr.

37° " 101.0

.38° " 97.2

Rate of
Observed climl) in
time Aneroid ft.
0.0

1.0 835
2.10 735

Density ( = p)
Observed referred to Observed
temp. standard density airspeed V X Vp
31 0.879 80.0 83.6
31 0.879 85.0 87.8

Correction

necessary

X3.6

X 3.8

3,000
4,000

36°
36°

94.0
90.7

3.70
5.40

640
560

31 ■
31

0.881 85.0 88.1
0.862 86.0 88.8

X3.1

X 3.8

5,000

36°

87.4

7.25

510

Mean X 3.1

6,000

33°

84.7

9.40

450

7,000

30°

82.1

11.90

405

8,000

26°

79.9

14.25

365

TABLE VI

9,000

22°

77.6

17.00

330

10,000

23°

74.7

20.25

310

AiH Si'EED AT Heights

11,000

21 o

72.2

23.60

280

27/12/16

12,000
13,000
14,000
15,000

20°
17°
12°

8°

69.8
67.7
65.9
64.1

27.40
31.90
37.90
45.25

230

^95

Aneroid

Corresponding
Temp. Standard Standard Observed

Corr.
for calil)ra-

150
110

height

observed t

ensity height air speed

tion tests

3,000

39° F.

.9.35 2,900 95 m.p.h.

Real rate

5,000

35°

.875 4,900 93 "

of cliinh

From curve

7,000

30°

.831 6,900 88 "

(corrected

Standard

'/r of stand-

Rate of

9,300

24°

.767 9,000 81 "

for temp.)

height

ard density

Time

climb

10,800
12,800

19°
17°

.731 10,400 80 "
.683 13,600 72 "

83
76

1,000

99.10

1.30

775

13,800

13°

.664 13,400 68 "

718

2,000

9C.30

2.56

685

15,200

8°

.636 14,800 65 "

623

3,000

93,26

4.11

610

£44

4,000

90.25

5.85

545

495

5.000

87.35

7.80

490

Corr.

435

6,000

84.50

9.96

435

for

Observec'

380

7,000

81.80

12.40

385

density

R.P.M.

FiXAL Results from Cuhve

347

8,000

79.16

15.14

345

101 y.

1,380

Standard

3»

9,000

76.55

18.20

310

I02y3

1,280

height Airspeed

R.P.M.

394

10.000

74.00

21.61

280

looy.

1,240

3.000 103.0 m.p.h.

1,390

264

11,000

71.70

25.41

245

1,320

fi.500 100.5 •'

1,350

316

13.000

69.50

39.81

210

1,220

10.000 96.5 "

1,215

182

1.3.000

67.33

.35.13

170

1.300

13,000 94.5 "

1,180

130

14.000

65.17

41.88

130

88%

1,180

15,000 86.0 "

1,160

101

14,500

64.11

46.23

105

86y;

1,160

STALLEMOMETER-..

HAND CONTROL
LEVER

SERVO MOTOR

How the Sperry Automatic Pilot is installed on a Voisin battleplane

CHAPTER XXI

THE SPERRY AUTOMATIC PILOT

Incorporating a Gyroscopic Reference Plane and Clinometer for Aeroplanes — Its

Application for Military Purposes

By Lawrence B. Sperry

The efficacy of the Sperry Automatic Pilot
in fulfilling its three important functions, as an
automatic pilot, a clinometer, and a gyroscopic
reference plane, having been demonstrated and
established beyond question by numerous actual
trials, it will be interesting to note the various
military uses to which these functions can be
put. Let us consider their applications sepa-
rately, under the following heads :

1 — Reconnaissance.

2 — Fighting in the Air.

3 — Artillery Regulation.

4 — Bombardment.

Reconnaissance. In the reconnaissance ma-
chine, the Sperry Automatic Pilot, by relieving
the aviator of the nervous and physical strain
incident to flying, enables him to rest while en
route to the area of reconnaissance, so that he
can conserve his energy for the more important

military operations that he is shortly to carry
out. If wounded, he can go on or return,
spurred by the confidence of knowing that his
aeroplane does not dejjend upon his own dex-
terity, but that of a tireless mechanism. If he
finds himself suddenly enveloped in a cloud, he
will be spared the incident nervous bewilder-
ment with its resultant effect upon his ability
to reach the spot set out for; in this connection
he is able to check his position by reading the
ever present clinometers on the gyro unit.

At the place to be reconnoitered, the pilot-ob-
server can study the positions below him
through his binoculars, without being hindered
by the increased effort necessitated by the mo-
tion of a less steady aeroplane, and without the
distraction of suddenly finding his machine
tipped to a large degree, involving a consequent
loss of time in again finding the position he was

269

270

TEXTBOOK OF MILITARY AERONAUTICS

Hand Control I.ever

observing, and even though shells might be
bursting around him.

He can take his feet off the pedals, perch him-
self sideways in his seat, and rest his sketching
board on the side of the machine, while drawing
maps or making notes; these actions being fa-
cilitated by the steadiness of the machine. An
observed position being worthy of a photograph,
he can be sure of securing the desired field in
his exposure, due to the machine retaining its
relation to the true horizontal and remaining
perfectly steady.

Being the observer, as well as the pilot, the
aviator can carry out, with an efficiency impos-
sible through the joint action of two individuals
acting as pilot and observer, respectively, those

manoeuvers in piloting that are necessitated by
the situation at hand, as seen through his own
eyes as observer. In other words, there are
eliminated the inefficiency and loss of time apt to
occur when two men are employed, due to mis-
understood or badly carried out instructions on
the part of the pilot, who is usually above the
rank of the observer, and who may have his own
ideas as to what should be done.

Owing to the device, the pilot-observer can
stand in his seat to review his rear in seaich of
an enemy machine. If attacked, he will have
the advantage of increased climbing and man-
CEUvering ability, due the elimination of an ex-
tra passenger and to the unusual efficiency and
easy control made possible by the never-tiring
Automatic Pilot. With this device the tail of
the machine can be slapped up, in order to get
in quickly and to stay in the non-fire zone of the
enemy, who is perhaps also diving. Thus, with
the enemy's landing chassis or planes nicely in-
terposed, the pilot-ol)server can stand up and
take deliberate aim with his rifle or machine-gun,
resting the rifle on a part of the steady aero-
plane, or steadying the machine-gun in its
crutch.

Fighting in the Air. In the single-seater
gun-scout, the Automatic Pilot, permitting the
selection of a supersensitive, efficient aeroplane,
will convert it into a steady gun platform, at the
same time bettering the aviator's mananivering
ability. A steady platform means accuracy of

The Anemometer.

Servo Motor — Cover Ueniovcil.

THE SPERRY AUTOMATIC PILOT

271

aim and ease in reloading, while, should the
gun become jammed, the pilot has a better
chance of fixing it without returning to the
ground.

Let us turn to the very powerful gun-
carrier, where it is thought advisable to
carry two men, one sitting in the nacelle,
between the two motors, back of the planes ;
the other in the nose of the same nacelle.
On such a machine, the device has the de-
cided advantage of increasing the cone of
fire, since the pilot can operate a machine
gun in a rearward cone, in the event of
the enemy outmanoeuvering him, or in
the event of his being attacked by two or
more machines at once. On approaching
combat, with the Automatic Pilot perform-
ing the more irksome task of correcting
the many disturbances, the aviator, thus
freed, can scrutinize his enemy with the
view of finding the limits of his non-fire
cone, his speed, vulnerable spots in the
enemy's craft, and other points that will aid in
planning his own manoeuvers of attack. This
increased freedom on the part of the pilot gives
him the chance of spotting with ease the differ-
ent enemy machines that he is about to attack,
thus preventing him, if he is endowed with a
sense of proportion, from inadvertently getting
into a position where he can do little or no good,
since he knows that two enemy machines are
four times as formidable as one. It should be
borne in mind that the hitherto great physical

The Gyroscopic unit.

exertion on the part of the pilot in moving large
controls is eliminated.

Regulating Artillery Fire. In the machine
for regulating artillery fire, the work of the
pilot-observer is cjuite similar to that involved in
reconnoitering. Pie will therefore be aided in
a like manner, only instead of the device facili-
tating the use of the sketching board and
note-book, it aids in using the radio or flash
signal.

Bomhardment. For purposes of bombard-

Aeroplane equipped
with Sperry Automatic
pilot.

272

TEXTBOOK OF MILITARY AERONAUTICS

ment, there is the machine of unusually large di-
mensions, which is capable of more nearly equal-
ing the performance of Zeppelins, so far as
staying in the air for long periods is concerned,
and at the same time is roomy and is able to
carrj' not only all conveniences in the way of in-
struments, but a large number of bombs. For
operating at decreased radii, there is a small
machine.

The evident advantages that the Automatic
Pilot secures in bombarding operations are the
following:

The facilitating of night-flying.

The accuracy and simplification of bomb-
dropping.

The elimination of one man.

The reduction of jihysical effort on the part
of the pilot.

Night flying. The bewilderment that comes
on a dark night, due to the pilot's imperfect

A — Gyroscopic I'nit. C — Hand Control Lever. E — Search I.i(tht

B— Air CoinpaHs. D— Drift Indicntor. V -Aiicinomctcr.

G— Scno .Motor. H— Hand Cut Out Switch

sense of horizontality, is accentuated to a high
degree when he is unable to secure those visual
impressions that he is wont to use in the day-
time. xVt night the pilot nmst depend for his
sense of horizontality, experts tell us, on the
reflex actions of certain semi-circular canals lo-
cated in the interior of the ears and tactile im-
pressions coming from the nerves, particularly
those in the soles of the feet and other support-
ing portions of the body. It is not generally
known that these impressions are susceptible to
serious error, due to centrifugal force or ac-
celeration pressures, which are cajiable of repro-
ducing and even multiplying gravitational sen-
sations, when the machine approaches an un-
accustomed inclination. The misinterpretation
of these sensations has often resulted disas-
trously.

Bomb Dropping. In bomb-dropping it is
quite needless for us to discuss the absolute ne-
cessity of having a gj'roscopic horizon-
tal reference plane of integrity and
accuracy, or to emmierate the inac-
curacies to which pendidums. mercury
tubes, and other gravity devices are
suscej)tible. Oin- experts have long
ago exi)osed the total unreliability of
all of these devices.

The gyroscoi)ic apparatus is capable
of staying within one quarter of one
degree to the true horizontal. A
sensitive aeroplane is held, through
the intermediary of the servo motor
and follow-up system, within three
(]iiarters of one degree of the position
oi" this gyroscopic plane. This varia-
tion of three quarters of a degree
might seem to the layman to be in
effect a corresponding inaccuracy, but
any one accustomed to reading a bara-
graj)li. the index of which is designed
to tremble or vibrate constantly, will
appreciate the ease and accuracy with
which the pilot bomb-dropper can se-
cin-e his objective in the mean of two
extreme positions, especially when
close to each other. In this way more
accurate results can be obtained than
with non-oscillating conditions, be-

THE SPERRY AUTOMATIC PILOT 278

cause this motion makes all the parts of the tudinal wire before releasing the bomb when it

follow-up mechanism extremely sensitive, as in reaches and crosses the lateral wire.

the case of the baragraph. Furthermore, the The increased accuracy of bomb-dropping

slight motion assures the operator that the ap- from an aeroplane equipped with the Automatic

paratus is functioning properly, while he need Pilot is due to:

only consult his clinometer located on the gyro 1. Being able to get the aeroplane more ac-

unit to check up accuracies, curately laterally over the target.

The proposition to connect the bomb-sight di- 2. Be4ng able to release the bomb at the
rectly to the gyroscopic element involves ham- proper angular distance from the target,
pering its freedom by friction of the connecting 3. Simplifying the operation of bomb-sight-
links, and by the inertia vibrations of the sight ; ing, since the sight is held automatically and ab-
in addition, pressure of the hand in making ad- solutely horizontal, thereby allowing the pilot
justments is likely to cause inaccuracies. It bomb-dropper to focus his entire attention to
is always advisable to leave the gyro as free adjusting the sight and steering the aeroplane,
and unmolested from outside forces as possi- During the long night bombardments, the
ble. elimination of the extra passenger has the ad-

With the bomb-sight rigidly fixed to the side vantage of either increasing the radius of action

of the machine or to the floor, the method of or of enlarging the bomb carrying capacity of

sighting is somewhat as follows : the machine; while, of course, in the event of

With the gyro manual control, the position of failure, one man is lost instead of two. The
the aeroplane is adjusted until both clinometers physical work of which the i)ilot is entirely re-
read zero. The operator then secures by his lieved in long bombardment trips, especially
rudder the motion of some objective in his field" with the larger types of aeroplanes, would fre-
of vision, parallel to the longitudinal cross wire, quently be too much for the ordinary pilot.
During this time the deviation angle is set by The important military functions for which
taking the usual stop-watch readings, or other the Sperry Automatic Pilot has been utilized
steps involving this very simple operation, demonstrate that it is essential to bringing the
The pilot bomb-dropper has now only to keep aeroplane to the highest point of military effi-
his ultimate objective moving along the longi- ciency.

The Ilandley-l'afre Warplane wliicli is equipped with two Holls-Royce motors of !?80 H.P. eaeh and lias iiiounlings for four
guns. It has wing span of 98 feet and is 65 feet long. It has carried 2 passengers in one flight

CHAPTER XXII

THE CASE FOR THE LARGE AEROPLANE

By F. ITaxdley Page, A.F.Ae.S.

The question of aero])lane size is a most iin- cheaper to run than small ones, and thus prog-
portant one. It raises the whole (juestion as to ress is seen in every type of mechanical trans-
whether there is, or is not, a limitation to aero- port towards the employment of larj'cr and
plane size, and therefore whether progress in larger machines with a view to taking full ad-
construction will he limited to improvement on vantage of the economies effected,
present-day small tyi)es of machines, or whether In an aeroplane there could, however, he no
there is an infinite ])ossil)ility in the extension of advantage in the use of large machines if Ihat
designs to much larger types. increase in size gives a dis])r()portionatc increase

It has heen argued hy many that, just as in weight which would more than nullify con-
ships, trains and other machines for transport structional advantages, or if the large aeroi)lane
purposes increase in size as years go on, so will had aerodynamical disadvantages. The whole
the aero])lane progress, and that the larger aero- case needs most careful examination from all
plane will have a definite place in the field of ])oints of view.

aviation. Others have adopted the opposite In the argimients set forth below I have

view. endeavored to compare machines of different

The general consideration in favor of the size and review their relative advantages, de-
large machine is that although tliere is a heavier tcrmining first of all hases of comparison to
initial capital outlay, large machines are nmch cnaljle a true picture to l)e ohtaincd. As these

cheaper to build, cheaper to maintain and necessitate the explanation of a new method of

274

THE CASE FOR THE LARGE AEROPLANE

275

aerodynamical composition I have set this forth
at rather greater length than is necessary for
the development of the argument proper.
After a discussion of the aerodynamical prob-
lem I have dealt with the effect on structural
weight of an increase in the size of aeroplane,
and then turned back to find the effect on the
aeroplane's performance of the weight variation

/^'-^^^

^ vt ^i^

"^ t4 %^

^ 'tl ^v^

. r 3^v-

^1-1 X

71 7 '

Jj tl

j2 Zz

-n /y

0_ L_ _ i_J$Ut_ i_ S_ —

with size increase. Lastly, there are a few
notes on the large machine from a flying stand-
point. It is a matter of some difficulty to ob-
tain a true basis of comparison from pilots'
opinions. Pilots are, as General Brancker re-
marked in his paper, a very conservative body,
opposed to innovation, and the machine of the
moment's design is not necessarily the one of
the future, or the one from which future ma-
chines will be developed.

Aerodynamical Bases of Comparison

To determine the calculated performance of
any machine it is necessary to have available
the wind-channel experiments on the Lift and
Lift/Drag of a large number of planes as well
as the resistance for various types of bodies
similar to that proposed to be used. The curves
of Lift and Lift/Drag are usually plotted in
absolute units and in the form shown in Fig. 1.

From these wind-channel curves the perform-
ance of the whole machine is obtained.

After the general details of a machine's de-
sign are settled, such as the weight to be car-
ried, the area of the planes, etc., the jjlane re-
sistance at various speeds are found from the
Lift and Lift-Drag curves. To these values
are added the correct ones for body resistance,
the values of the two curves added together and
the total horsepower required calculated for
different speeds. When the engine power and
propeller efficiency is known, the curve of avail-
able horsepower can be plotted and the ])oints
of intersection of the two horsepower curves
mark the limits of aeroplane speed variation.

It is quite easy to See that this method, al-
though exceedingly useful for any particular
aeroplane, does not afford a quick means of
comparison between a machine with })lanes of
different section or different shape or loading.
I have therefore adopted a different method of
plotting, so that the performance of any ma-
chine can be directly predicted from the wind-
channel tests, on the Lift and Lift/Drag of the
planes used, and on the body resistance, the new
method taking into account the effect of altered
loading or varying air densities at various
heights.

I will deal first of all with the plane calcula-
tion.

The following is the notation adopted :

V — velocity of the aeroplane in ft./sec.

W — total weight in lbs. of the aeroplane.

A — area of main planes in sq. ft.
— density of the air in Ibs./cu. ft.

9 —32.2.

Km — absolute value of the Lift Coefficient.

Kt — absolute value of the Drift Coefficient.

JRft — total body resistance in absolute units
per ft. per sec. of the aeroplane con-
sidered— i.e., resistance of the chassis,
body, struts, in fact all the resistance
of the aeroplane except that of the
planes.

The following equations maj' be written:

whence
V

_ _T_ \\V_ 2.
VKu yJAe

■ (1)
• (2)

276

TEXTBOOK OF MILITARY AERONAUTICS

where

F-^a

VKy

• (3)

JF g

Resistance -- Kx . - . A . V
9

H.P. = Kx .- . .V^ .

9 550

(4)
(5)
(6)

Inserting the value of V from equation (2)
above

H.P. = K^/-.^„(4'.^)'

g 550 \A e I

Whence

^^~Ky\Ky 550 \ A e

H--=^-^;^^

WTiere

550 ^ A. e

Summarizing

H.P. = h

Kx FT

Ky\Ky

(7)

(8)

(9)

(10)

(3)
(9)

Instead of the usual Kx and Ky curves for a
plane there will now be plotted

1 Kx
and -Y^

Ky Ky

- /-1_

which is equivalent to plotting h.p. required
against velocities. A curve for the section
known as R.A.F.6 and one for the section
known as R.A.F.3 have been plotted out in this
way. It is well to examine these curves to see
their general application before jjroceeding to
deal with the question of plane comparison. In
Fig. 4 are plotted the ordinary Kx and K*
curves for R.A.F.6 and R.A.F.3, R.A.F.6
has the lower value of Kv maximum and higher
value for Kv/Kx. The maximum value of K»
for R.A.F.6 is .605, and that of R.A.F.3 is .695.
The result of this is reflected in the curves in
Fig. 3 where R.A.F.3 gives a slower landing
speed than R.A.F.6 for the same loading. The
slow si)eeds are related in the ratio of the sq.
root of their maximum Kv or in the ratio of 1 to
105. These plotted curves give them the rela-
tionship between h.p. and velocity for ecjual
loading. If it is desired to know the actual
speeds obtained with different h.p. or in effect
to obtain the correct scale for these curves it is
only necessary to obtain the multiplying factor,
converting the horizontal scale into feet per sec-
ond and the vertical scale into h.j). This is done
by evaluating the constants a and /; in equations
4 and 10 above, inserting therein the correct
valuation of JV, A and e/g.

Attention is drawn to the fact that the load-

The British Handley-PHge gun «nd l)oml)in(( plane. It hns carried twenty-one passengers. (British Officiai.)

THE CASE FOR THE LARGE AEROPLANE

277

ing expressed in weight per unit of area, and the
value of the density of the air expressed as
weight per cubic unit of air, appear in the same
form in both velocity and h.]). multiplying fac-
tors. It follows, therefore that these curves are

t*-

...' .

-7^

«,"/'■?. 3 I

• **

-■'■-- -' wJ

' "'"J

-ioo^i «M — «i_a

correct for any loading or height above ground
level, the comparison between the two being
correct as long as the loading is equal in both
cases. The onlj'^ alteration is the multiplying
factor of the horizontal and the vertical scales.
It is hardly correct, however, to compare two
machines, one of which has a slower landing
speed than the other. For correct comparison
the slow landing speed of a machine fitted with
planes to R.A.F.3 section should be increased
so that it is the same as that for R.A.F.6. The
area of the R.A.F.3 ])lanes should be decreased,
thus increasing the loading until the two slow
speeds are identical. The loading is increased
in the ratio of 1 to 1.0.5. To compare the re-
sulting curves it is better to keep the multiply-
ing factors of the vertical and horizontal scales
the same and alter the R.A.F.3 curve. Since
the loading enters into the multiplying factor
of the h.p. and velocity scales equally each value
of the R.A.F.3 curve must be increased 1.05,
both as regards h.p. and velocity. A new curve
is now obtained for R.A.F.3 having the same
slow speed as R.A.F.6 and the multiplying fac-

tors being the same for both. These new curves
will again be true for all heights.

We will take an actual practical example.
Assume a machine weighing 2200 lbs. with a
loading of 5.9 lbs. per sq. ft., and that at the
ground -p/g — 425. Then from equation (4)
a = 50 and from (5) h = 200. For R.A.F.3
the value of Kv (maximum) is .675, and of
M^Kv is 1.215. For R.A.F.O the value of Kv
(maximum) is .605, and of \/\/Kv is 1.285.
The slow landing speed of R.A.F.6 for the load-
ing of 5.9 lbs. per sq. ft. is 50 X 1.285 = 64 ft.
per second or 43.5 miles per hour. The slow
landing speed of R.A.F.3 for the loading of 5.9
lbs. per sq. ft. is 50 X 1.215 = 60.5 feet per sec-
ond or 41.2 miles per hour.

The new curve for R.A.F.3 will be for a slow
landing speed of 43.5 m.p.h., and the loading

will now be

43.5
41.2

X 5.9 = 6.25 lbs. per sq. ft.

Each point on the old R.A.F.3 curve must have
its vertical and horizontal value increased in this
proportion — i.e., multij)lied by 1.05. The new
R.A.F.3 curve was plotted in this way.

The minimum height of either of these curves
above the horizontal is the minimum h.p. re-
quired by the planes, and, neglecting body re-
sistance, the curve with the minimum value will
have the highest climbing speed. It must al-
ways be borne in mind that the curve with the
higher loading will have the smaller planes, and
therefore weigh less. Allowance must be made
for this in effecting the comparison.

The three curves can now be compared. For
the same loading and h.p. available R.A.F.3 has
the slower landing speed, the higher climbing
rate, but the slower top speed. If the loading
be increased R.A.F.3 loses its advantage in
climbing rate, and does not attain the same high
speed as R.A.F.6. In a similar manner any
other or more modern planes may be compared.

It is interesting to note, in passing, that at
10,000 ft. height where ip = 0.55 the value of a
will be increased to 59 and of h to 236. The
effect of height is to reduce the h.p. required for
any given speed, and also the speed range by
increasing the slow speed. Owing to the h.p.
scale being increased, the minimum h.p. re-
quired for flight is increased, and, therefore.

278

TEXTBOOK OF MILITARY AERONAUTICS

quite apart from reduced engine h.p., the excess
h.p. available for climbing is reduced.

The general range of velocities for a high
speed machine is from 50 to 130 m.p.h. or 73.5
to 190 ft. per sec. In general the value of
l/VATv will he between 1.4 and 3.8. For a slow
speed machine flying from 40 to 90 m.p.h. or
59 to 132 ft. per sec. l/VKu will vary between
1.1 and 2.7. Any comparison between plane
ounces must be made between the velocity limits
of the type of machine considered.

So far the comparison has only been extended
to the planes of a machine. The body of re-
sistance remains to be dealt with.

The e(juation may be written :

Resistance = i?t .-. F" . . . . (11)
9

H.P. required — Rb

■H

550

(12)

This equation is identical in form with the
plane h.p. curve. The term Jib is the product
of tlie values of a resistance coefficient K^r^
and a body area S. The equation may there-
fore be written: —

H.P. required = Kivb .^ .f-- V . (13)
' (/ 5o0

Whence inserting the value of V in equation
(2) above

H.P. required =^^-^ 4. I^^f j-

(U)

The H.P. required for body resistance can be

plotted to the same scale as those for the planes.

The values would be divided by

W_ \W g
550 \ A ' p'

There would then be plotted for the body re-
sistance H.P. the value of:

Kxb\KyA • ' • ^^^^

The h.p. required for body resistance can now
be added to the plane h.p. curves. Let us as-
sume that the machine referred to in paragraph
10 above requires 10 h.p. to overcome body re-
sistance at 100 ft. per sec. Below the horizon-
tal line has been added a curve of h.p. retiuired
to overcome body resistance, the scale of h.p. be-
ing the same as that for the planes. The total
height between the two curves for any value of
l/\/Kv gives the total h.p. recjuired at that
speed. It is interesting to note that these curves

rartUl view of tlic Cuproiii Tri|iliiiu- vqui|i|)f<l Willi tlirct' iiiuturi. ut' iW li.|>. This iiiailiiiir hns ii wing spreiid of 101 fi-ot.

THE CASE FOR THE LARGE AEROPLANE

279

are correctly placed in respect of one another
for all heights. This method of plotting and
the curves so obtained give the necessary basis
for a comparison between different machines,
and reference will be made to them again later
in the pajjcr, after discussing the structiu'al side
of the question.

The Effect of an Increase in Size on the
Structural Weight of Aeroplanes

^Vttention has already been drawn to the fact
that an improvement in the aerodynamical qual-

4i^

^ - lU

-tt

Mt.

^ dnU^

" ■ m

^ tkt

/// - -

— ->tt

M-

//^

^■^

a_ U<>_. i i

ities of the machine as the size increases may be
partially or completely nullified if the increase
in size is accompanied by a disproportionate in-
crease in weight. I will, therefore, accordingly
examine the rate at which the weight increases
with increase hi size.

In this discussion we shall leave out the
weight of the power unit comprising engine,
tanks, and fuel, as well as the useful load,
whether consisting of men or dead weight, such
as guns, bombs, etc. We will confine our argu-
ment to the weight of the machine structure,
that is, the portion which supports the load
whether on the ground or in the air, with the
necessary directing surfaces and their attach-
ment to the main portion of the aeroplane. In
the latter category come the planes, the fuse-

lage, and the chassis, and these will be considered
seriatim.

In all discussions on weight saving there is
the general question as to the best utilization of
materials with the varying size of machines.
As the machine is made smaller, so eventually
a limit is reached beyond which it is not possible
to decrease the minimum thickness of the
material and retain adecjuate local strength.
Especially is this the case in aeroplane work,
where the members are usually stressed as
struts, and for which, therefore, a hollow tubu-
lar construction is the most efficient form from
the point of view of mininumi strength for a
given weight. In making tubular members,
whether these be plane spars, fuselage, struts,
or longerons, it is not advisable to decrease the
thickness of the walls below ^/u\ in. to Vi in.
Even this is on the small side when allowance
is made for errors in workmanship, and the fit-
ting in of the necessary tongue piece to make
a secure joint. Considerable economies can be
effected in weight-saving with increase in size
in this manner.

Local strength, too, determines the construc-
tion of subsidiary parts of the machine, such as
the tail skid, the ribs, tail planes, a local strength
that does not need to be increased with inci'case
in size of the machine, and here, again, weight
economy can be effected.

This better utilization of material more than
offsets the increase in weight that would occur
in the planes provided that they were increased
in a geometrically similar manner and the load-
ing aspect ratio and section kept the same. In
a machine of which I can show you the })hotos
later the plane weight per square foot is less
than a small one for the same factor of safety,
and the total plane weight is a lesser percentage
of the gross weight.

The fuselage weight, owing to the better util-
ization of material, is considerably decreased.
The chassis weight remains about the same.

The Effect of an Increase in Size Upon an
Aeroplane's Performance

A general comparison can now be effected be-
tween aeroplanes of different sizes on the basis

280

TEXTBOOK OF MILITARY AEROXAUTICS

of the curves described in Section II, the total
weight of the aeroplanes considered being modi-
fied according to the size in accordance with the
conclusions of Section III. An examination of
equation Xo. 9 in which H.P. equals /; X Kx/Kv
XVl/Kv shows that, provided that similar
planes are used and that the weight per H.P.
remains the same, the same plane curve repre-
sents all machines. These curves as plotted are,
in fact, curves of H.P. required per pound
weight of the machine for a given loading per
square foot. Let us now examine the lower
curve of H.P. required for body resistance and
refer to equation 14. Provided that the area of
the body increases in the same ratio as the plane
area, this lower curve will still, for any size of
machine, be correct in relation to the plane curve
plotted above, and the summation of the two
ordinates or the distance between the two cin-ves
will represent the total H.P. required, the scale
being increased in proportion to the increase in
ratio. The greatest resistance of an aeroplane
is that of the body. This, for smaller shaped
bodies, would increase as the square of its lineal
dimensions, whereas its volume would increase
as the cube. It follows, therefore, that the re-
sistance of the fuselage per unit of volume will
decrease with the increase in size of the aero-
plane. The lower curve will have to be modi-
fied to meet these changed conditions. This de-
crease in weight will have the usual cumulative
effect of decreasing the weight of all the rest of
the machine.

The curves which are plotted are for H.P.
per unit weight of the whole machine, and do
not show so graphically the su])eriority of the
large machine as if the curves of H.P. per imit
of useful weight had been plotted instead of
gross weight. In this case the curves for jjlanes
and body would have their vertical ordinance
increased with the projjortion of useful to total
weight. The balance in favor of the large ma-
chine is tiujs apparent directly we com])are ma-
chines of approximately the same total weight
per H.P.

The conclusion that may be drawn from the
above theoretical considerations of the aero-
dynamical and structural ({ualities of the large
machine are that for the same total weight car-

ried per H.P. the big machine will effect the
better performance.

The Large Machine from the Pilot's
Standpoint

There has been very much less experience in
the flying of large machines than with small
ones, and, therefore, pilots are not so accus-
tomed to their use, neither is the experience wide
enough to draw general conclusions. It may,
however, be safely said that large machines can
be built to operate quite as easily and fly with
as little fatigue as the best of the small ones.
Xo Servo-motors are required for the controls,
provided the controlling surfaces are properly
balanced. There is less work in flying a large
machine owing to the wind gusts, which seem
large to a small machine, being relatively small
in their effect on a large one. A large machine
will plow its way through gusts without any
control being necessary, whereas a good deal of
war})ing might be necessary on a small machine.

Vi-

' ~

—

■^^

The large machine can be handled more easily
on the ground and can alight in smaller places.
When considered from the point of view of
load to be carried or long distance to be flown
the large machine has it all its own way.
^Vhere a large load is to be carried the size of
the machine to do it must be increased until the

THE CASE FOR THE LARGE AEROPLANE

281

These men coni])ri.sc the first firniip of Ainerieiin aviators wlio rejiresentcd U. S. on the i-'rench front. In tlie group, ielt lo right
are: Lieiitcnant de Laage, Sergeant C. C. Johnson, New York City; Corporal Lawrence Uunisey, Buffalo, N. Y.; Sergeant
J. H. MeConnell, Carthage, N. C; Lieutenant William Thaw, Pittsburgh; Sergeant H. I.ufhery, N'ew Haven, Conn.; Sergeant
Kiffin Rockwell, Atlanta, Ga.; Adjutant Didier Masson, Los Angeles, Cal.; Sergeant Norman Prince, Boston, and Adjutant
Bert Hall, Galveston, Tex. [Photo Courtesy N. Y. Times.]

useful load is sufficiently great. The size of the
machine that is required for the purpose de-
pends on the total weight per H.P. that can he
carried. There is here no (juestion of competi-
tion between large and small machines, it is a
case of the correct machine for the purpose.

For future commercial developments the
large machine scores with plenty of room for
passengers to sit in comfort, or mails or lug-
gage to be carried, and with its steadier move-
ment will afford great comfort to those who
travel by it. It is probable that commercial
aerojilane work will be undertaken for long-dis-
tance journeys. Where delays at the com-
mencement of the journey are a large percent-
age in time of that necessary to complete the
distance, the possible time taken to traverse a
given space may be as great or even greater
than that taken by a more certain means of
transit. It is the old question of the hare and
the tortoise. Where, however, the distance to
be traversed is great, such as 1,000 to 2,000
miles, or with journeys such as crossing the At-
lantic, the passengers or mails could afford to
wait a day or two and will accomplish the jour-
ney far quicker than any other means of transit.
Were the commercial development of aviation

confined to journeys of from 50 to 200 miles,
delays at starting or the cost of organizing to
prevent them would cause the aeroplane's use to
be considerably nullified.

It is this question of certainty in operation
that requires careful attention, for it is the one
thing at the present time that the aeroplane re-
quires in order that it may take its proper place
in commercial work. Engines for this will
probably be more heavilj' built to reduce the
possibility of breakdown, and multi-engine ma-
chines will be used which can fly satisfacto-
rily even if one engine breaks down. Here
again this points to the use of the larger ma-
chine.

Finally, it must be pointed out that the same
improved performance can be obtained from a
large machine, whether for scouting, fighting,
or weight carrying, provided that the specifica-
tions are the same in both cases. It is absurd
to compare the performance of a weight-carry-
ing machine with high values of useful weight
per H.P. with a small scout of very small use-
ful weight per H.P., and particular attention is,
therefore, drawn to the methods of com])arison
set out in Section II, so that careful comparison
mav result.

Memoranda:

CHAPTER XXIII

EVERY MILITARY AVIATOR OUGHT TO KNOW WHAT HIS OWN AND
THE ENEMY'S MACHINE CAN DO AND HOW THEY LOOK

(Courtesy of Aerial Age Weekly)

"If you see an aeroplane that does not look
like any of the machines shown in this leaflet,
you are to make every eflFort to bring it down."

This, in eflFect. is the instruction that every
French and Italian aviator receives, not only
while he is being instructed, but periodically,
whether he is at one of the permanent military
aerodromes or temporarily stationed on the
front.

The Allied Governments found it necessary
to teach their aviators and students all about
their own machines and as much as possible
about the enemy's machines, particularly their
appearance. As a basic principle, the aviator
is taught that what does not look like one of the
Allied machines must be an enemy machine.
Therefore every effort should be made to bring
it down.

The anti-aircraft forces are taught the same
thing, and knowledge of the features of the
different types of aeroplanes is one of the prime
factors in making anti-aircraft forces efficient.

Lacking that knowledge, the Allied air forces,
as well as the anti-aircraft defenses, get confused
and pernn't the enemy to obtain temporary ad-
vantages which cost the lives of Allied aviators,
as well as of the ])opulation of cities which are
raided, without mentioning the strategic advan-
tages that the enemy gains through gathering
information or surprising the Allies.

It has also been found of extreme importance
to have every aviator know what the enemy's
machines, as well as his own machines, can do.
It will be recalled that when the first "Spad"
appeared, the CJerman aviators did not give it
credit for the speed it had, so they ventured too
much and too far for their own good. The
Cigogne S(|uadron and the Lafayette S(]uadr()n
were enabled thereby to maintain supremacy in

the air and to bring down a number of German
aviators who did not know the fighting charac-
teristics of the "Spad."

In several cases some of the machines which
were thought to have " blind sides " were found
to have guns mounted at front and rear, and
to shoot below as well. An aviator in a single-
seater fighter would attack what appeared to
be a "pusher type," and all at once a gunner
would emerge from the small cock-pit and turn
a stream of fire on him.

The United States is to train thousands- of
aviators, observers, aerial photograjjhers, and
anti-aircraft gunners. Many are taking their
])reliminaiy course, and thousands are waiting
their turn. Thousands more of prospective
candidates are not yet of age, or have passed
the draft age and will volunteer as they learn
more about military aeronautics. INIilitary and
aeronautic authorities agree that a valuable
service can be rendered to the nation by contin-
uing to publish descriptions of machines used
by the enemy, as well as by the Allies. In the
last case it is necessary, of course, not to publish
details of machines which the enemy has not yet
caj)tured, or to give details of performances of
newly adopted types. In a general way, any
type that has not been used in number at the
front for a period of at least two months must
be considered as new, and details of perform-
ances must not be published.

The publication of details of German ma-
chines is encouraged. The Boche knows, of
course, all about his own types; he also knows
how the Allied aeroplanes look, as soon as one
or two are captured. But he docs not always
know all about performances. Thcrcfoi'e, in-
formation about performances of new types
should be withheld.

282

Sopwjtli Triplane (British), 'i'lie motor, a rotary Clcrget, is
completely surrounded by an aluminum cowling. The planes
are equal in span, very narrow in chord, and braced by a single
strut at either side of the fuselage. Planes highly staggered.

De Havilland 2 (British). Somewhat resembles the F. E. 8,
but the outriggers meet one another at the vertical rudder in-
stead of at the tail plane.

Sopwith single-seater (Britisli). Used by the French and
British. Also the Sopwith two-seater. Equipped with a rotary
engine, Clerget or Rhone. Identified by the central set of
struts, which stagger outward at the upper end. The fixed
triangular fin is rounded off at its leading end. Planes are
considerably staggered. Ailerons on both upper and lower
]ilanes.

Koland two-sealcr ((jerniaii). The engine is a fixed .Merce-
des, 175 h.p. A machine-gun and bombs are carried. The
body is exceptionally deep, reaching as high as the upper j)lane.
Windows are provided in tlie sides of the fuselage for observa-
tion. There is but a single interplane strut at either side of
the body. Planes are considerably staggered. Fin and rudder
placed very high.

F. E. ^b and 2d (British) (Farman Experimental). Pusher
type with a nacelle which carries a fixed Beardmore or liolls-
Hoyce engine. Empennage carried on four outriggers. Land-
ing gear consists of two main wheels and two smaller auxiliary
wheels below the forward cock.

283

F. F,. 8 (British). Scout type single-seater pusher with a
rotary Monosoupape-Gnome engine. Fin and rudder area simi-
larly disposed above and below the tail-plane. Two-wlieel land-
ing-gear and tail-skid below the fin. A movable Lewis ma-,
chine-gun is carried on the deck of the nacelle.

Xioiiport. I '.'■ed hy the French, 15riti''h, Belgians, and Italians. Jlade in single-seater scouts which have rotary Rhone or Clcrgct
engines and having a small wing sjian, and also two-seaters with fix<'d Hispano-Suiza engines and a larger wing span. Struts be-
tween the planes arc V shaped. Two sealers have two sets of struts at either side, the outer sets inclined outward at the top.
Other struts are vertical.

Urcguet Av. (FrcTuhV Has a fixed Renault engine. Di-
hedral on the upper plane only. There are ailerons on the
uj)|)er and lower jilanes, the lower ones being exce])tionally
long and extending from the wing-tip nearly to the body. The
elevators are lialaiucd.

Hristol Scout (British). Called the "bullet." One of the
fastest scouts. I'ses a rotary Bhone engine. There is also a
Bristol two-sealer which has two pairs of struts at either side
of the body. The two-seater is equipped with a fi.xcd engine.

H. K. .'e nncl the B. K. U (British) (Bleriot Kxperiimnlnl).
Thev mnrhlnr', are equipped with fixed H. A. F. (Hoyal Air-
craft Factory) engincK with n four-bladed propeller. The
plntM^ are ttagfrrrrd and have a pronounced dihedral on lK)th
planes.

Vickers Scout (British). Rotary Clerget engine Single
pair of struts at either side of the body. I'lanes eqmd in area
and .similar in outline. High stagger. The engine is com-
pletely surrounded by an aluminum cowling.

284

13. E. 2e and H. K. 8 (British). There Is a single pair of
struts at either side of the l)ody, in addition to one strut which
connects each pair of ailerons on upper and lower wings.

R. E. 7 (Kcconnaissance Kxperimental) (British). Upi)cr
plane of greater span than the lower. Two pairs of vertical
struts at either side of the body and a pair of inclined struts
which carry the overhang.

Ariiistrong-Witworth (British). I'pper and lower planes
are practically similar in sha])e. They are not staggered nor
swept bacli, and have but a little dihedral. Two sets of struts
at either side of the fuselage. The fin surface is rather large
and carries the rudder quite high.

Paul Schmitt (French). Made in two types; the type B. K.
A. H. (Bombardment Henault, Ailes hautes) and the B. K.
A. B. (Ailes basses). The planes of this machine are arranged
to be altered while the machine is in flight, changing the angle
of incidence according to the lift recjuired.

Caudron G. (j (French). Quite similar to the R. 4, but two
rotary engines are used. It has only four landing wheels and
a very narrow lower plane. The upper ])lane overhangs con-
siderably and is braced by sloping outer struts. Trailing edge
very flexible.

Caudron R. 4. Used by the French and British. Twin-
motored tractor type with a fuselage. The landing gear is
composed of a pair of wheels below each motor corajtartment
and a fifth wheel at the nose of the fuselage.

Aviatik (Aviatik-u. .Autumohil-Gesellschaft) (German). A
fixed Mercedes 17.5 h.p. engine is installed. The familiar ex-
haust stock carries the gases from the engine and leads them
over the top plane.

Albatros CHI. A German "all purposes" machine which
carries a fixed and movable gun. Radiator carried in the
upper plane. Exhaust pipes similar to that of the Aviatik.

285

I.. V. O. (Luft-Verkehrs-Gosellschaft) (German). Made in two tj-pes: Type "D9" wliioh lias a 175 Ii.p. Mercedes or Benz engine,
nml Tyiw "1)11," having a 235 h.p. engine. Distinguishable by its "half-negative" ailerons and tlie long span of the Dll, tlie wing-
cbord of which is greater near the body than at the wing-tips.

AGO (Aktien Gesellschaft Otto). A German single-seater.
Rotary Olterursol ciigiiu- with propeller spinner or nose-piece.
The vertical rudder is balanced much in the manner of the
French Nicuport. The upper plane is but slightly greater in
span than the lower and both planes have practically the same
chord, whereas Ihe Nieuj)ort has a narrow lower plane.

Albatros D.III (German). Single-seater scout equipped
with a vertical Mercedes engine. A'ery apt to be mistaken for
a Nieuport, as it has V struts and a narrow lower plane. It
has, however, a high vertical fin and an undcr-fin tail-skid.

Fokkrr (German). Sinple-sonter scoiit machine, with a
rotary OIktutscI 100 h.p. or a fixed Mercedes 170 h.p. engine.
Tills ninchinc Is very similar to the Mornne-Saulnler, but Is dis-
tin|riii'>hflli)e l>y Its commn-shnped balanced directional rudder
ami ll« two pairs of interplnnr strnls. F.vidently if'! conslrue-
tors apprrriate the vnhw of adhering to Morane-Saulnier lines.

Halberstndt (German). Single-seater equipped with a fixed
Argus or Mercedes engine. The planes are staggered I'e",
and the upper plane slightly overhanging, thereby differing
from the Morane. Over-all length, 2V0'. Span, upper plane,
28' 0" 5 lower plane. 25' 10". Chord, both planes. S' 2". Gap.
4' 4". The bidanced tail-flaps measure 10' from tip to tip, and
are S" 4" wide.

Morane-Suuliiicr. Employed by the British. A rotary en-
gine is used, preceded by a streamline nosei)late. The under-
carriage structure resembles the letter M (initial of "Mora&e").

Martinside (British). Kngine is fixed. Ailerons on uji|)er
and lower planes which are about equal in span. The tail-
plane is narrow in comparison with its span.

Moruiie-Saulnier monoplane (used by French and British).
The Parasol type is equii)])ed with a rotBTy engine and resem-
bles the Morane-Saulnier biplane. ,. « ♦

JIorane-SAulnier monocoques 11 and 13 niq. It is often mis-
taken for a German Fokker, which is a copy of the earlier
Morane-Saulnier.

Farman Freres F. 40 (French). A pusher type biplane with
a fixed engine. The nacelle is situated above the lower plane.
Lower plane has the same chord, but about one third less area
than tlie ii])i)er. Ailerons on the ui)))er plane only.

De Havilland 4 (British). Uses a V-type engine and four-
bladed propeller. Plane's are slightly staggered, but not swept
back and very slight dihedral. Two pairs of struts used at
either side of the fuselage. A balanced type rudder used.

Salmson-Moineau (French). A tractor biplane with twin
propellers driven by a single Salmson engine. The propellers
are carried lietween the planes l)y means of X-shaped .struts.
The empennage surfaces are rectangular in shape.

Caproni H. K. P. (Italian and French). This is a .'?-motored
biplane with two motors in tractor position, located at the
front of the fuselages, and a pusher engine at the rear of the
central nacelle.

287

Spad single-sciitfr scout (Sooictc pour TAviation et sos
Derives). Used by the French and British. All Spads are
equipped with either IjO or :200 h.j). engines. This machine Is
easily confused with the Albatros, a German scout.

Alh.itros D. 1. Single-seater scout. (German.) One of the
fastest of German aeroplanes. It is equipped witli a 170 h.p.
Mercedes engine or a 25 h.p. Benz and provided with two fixed
machine-guns arranged to fire through tlie propeller.

A.K. or .\.1,.U. I'renili niacliine for all uses. Planes are
Jnvertly staggered and the fuselage is set above the lower
plane.

Uumjiler. (German.) Has the Mercedes 17,5 h.)). engine, a
fixed and a movable gun. Radiator semi-circular, set into the
upper plane.

["fc-*

Spad two-seater. (French.) Fixed engine. Similar in out-
line (and eonstruetion) to the Spad scout. The two-seater car-
ries a movable gun at the rear, in addition to a fixed machine-
gun syriclironized with the propeller and firing directly ahead.

A. E. G. (Allgemeine Elektrlzitiits Gesellsehaft.) A Ger-
man two-seater witli a 175 h.p. Merceiles engine. It carries a
gun synchronized with the propeller and one movable i^t the
red r.

I.rlonl. (Frrncli.) A three-pliini- twjn-iiiotiirrd biplane
Imrtor inlnji nxr<l rn(rlnc». The pinnrs nre sliiggered bnek-
ward and the struts are run verticolly backward at the tops.

288

Mnrnne-Snulnler twin-niotored. (French.) This is n tlircc-
plnce tractor with nacelles cnrryinK either rotary or fixed en-
gines. Two machine-guns are used.

Caproni Triplane (Italian). Italy's best known aeroplane, and the inrp-st triplanc built. It is (-(iiiipiicd with three I'iat or
I. F. engines; two located in tractor position at the front end of each fuselage, and one pusher at the rear of the pilot's nacelle.

Handley-Page (British) Twin-engine bonihing l)iplane. One of the largest machines built. It is equi])ped with two 12 cylinder
Rolls-Royce engines. It holds all world's records for large aeroplanes carrying from one (1) to twenty-one (21) passengers. Its
wing-span is 98 feet. It is identified by its biplane tail, the motor nacelles mounted between the planes, the large overhang of
the upper plane and the balanced ailerons. The undercarriage is composed of four shock-absorbing wheels and a small tail-
skid.

Gotha (German) twin-engine warplane. The machine used in a considerable number of raids on London and recently on I'aris.
Has a span of 78 feet and carries two Benz engines totalling to 4.50 in h.p. The machine bears a resemblance to the British Hand-
ley-Page, from which data for constructing the Gotha was obtained, but it is a pusher and the Handley-Page is a tractor. Identi-
fied by its overhanging balanced ailerons (similar to the Handley-Page) and its usual monoplane tail (differing from the British
machine which has a biplane tail). Three machine gxms are carried; one in the front, one at the rear cockpit and a third below
it, which can be fired downward and backward through a so-called "gun-tunnel" on the underside of the fuselage.

289

Kokker inunojWane (German). Follows closely the French
Morane, especially as to its balanced elevators. Equipped with
a rotary Oberursel 80 or 100 h.p. engine. One of the first
German machines to successfully employ a mechanically oper-
ated machine-gun firing through the sweep of the propeller.

Br^guet (French). Bombing machine of the pusher tj^pe.
Carries a light cannon or machine-gun. Landing gear has
tliree wheels. Two vertical fins and a vertical rudder.

Voisin (used by the French, British, Belgians, and Italians).
The engine is a fixed type. This is a pusher type bombing
machine, with a balanced rudder and a balanced elevator car-
ried on four outriggers which terminate in a vertical chisel
«lge.

Caudron G. 4. (Used by French, British, and Italians.)
Two rotary engines are carried in small nacelles between the
planes. The pilot's nacelle is situated between the motor
nacelles. The empennage is carried on four outriggers run-
ning back in line with the engines, the lower outriggers acting
as landing skids. Four vertical fins and four rudders are
located al)Ove the tail.

Avro (A. V. Hoe & Co., Ltd.) (British). The y\vro machines have an equal upper and lower wing-span. In the twin mo-
tored m;>chlne the engines are carried on the lower plane, with exhaust stacks running up over the upper plane. Vertical engines
■re uxed. A wheel Is located beneath each of the two engines. The two-seater Avro has highly st«ggere<l wings and a .slight
dihrdral. The landing gear is characteristic; the long central skid is located between the wheels, supporting V struts at either
end. The rudder is of the balanced "comma" type. There is no vertical fin. A rotary engine is u.-sed.

e«o

AMERICAN AEROPLANES, 1917-18

AECOMARINE

CUETI5S TRIPLANE

WITTEMANN- LEWIS

McLauqtiliri

AMERICAN AEROPLANES, 1917-18

WRIGHT- MARTIN 'F.B.A.' FLYING BOAT

McL^u^ghlin

INDEX

Abnormal weather conditions

"Aces" 63

Act of Congress

Acetylene process

Ader, Clement

Aders, Avion

Adhesive insulation

Admiralty, British

Advisory Committee of the Council

A. E. G

Aerial Airway, Wilson

beacon

beacon, French

combat

League of America

League of Germany

lighthouses

navigation

operations, independent

photography

reconnaissance

Reserve Corps

standard

supremacy

touring

Aerials 142,

Aerials, dirigibles

Aerials, methods of suspending

Aero bases

batteries

cameras, care of 100,

camera, Pabbri

Aero Club of America

186, 189, 199, 201, 202,

203. 204, 206, 209, 210, 211, 212,
214, 216, 217, 218, 219, 235, 237,
Aero Club:

France

Illinois .

Italy

Aerodromes 106, 125, 128,

Aerodynamic comparison

Aerodynamic forces

Aerofan

Aerofoil

Aeromap 197,

Aeromarine

Aero messages 117,

Aeronautic appropriation

cartograjjhy

communication

division, Signal Corps 204,

Aeronautic engineers

personnel, regulations for uniforms

Aeronautics 157,

Aeronautics at outbreak of war

Aeronautics, history, U. S. Army

Aero observer

-.70, 71, 72. 74, 91, 113. 114, 116,
Aero- Personnel Division. .. .180, 181, 182,

Aerophotography 91, 92,

93, 94, 95, 96-97, 98, 99, 100, 101,

102, 103. 104, 105. 106, 107. 108,

Aerophotography, directions

elevation

interpreter

methods

organization

plates

reading 98,

technical

Aeroplane aerial

and infantry

armament

armor

batteries

bombs

cannon

collapse

communication

contact patrol Ill,

De Laison

Aeroplane equipment

fighting

first use for military purposes

for spotting

guns 48,

installation, wireless

invisibility at night

leading American

measurements and performances

metal construction

night flying

night landing

night patrol

performances

problems of construction

radio equipment

radio set, Washington

259

64
205
177
240
240
145

91
214
266
200
286
133

63
199
231
134

23
7
198
157
212
146
3
203
143
143
143

74
106
103

238

203
201
202
130
275
256
154
252
202
291
118
214
200
139
205
245
190
159
240
204

142

185

109

108

101

104

105

146

121

119

133

113

231

145

125

242

250

125

135

125

379

245

139

153

Aeroplane equipment — Continued

searchlight

signals from ground

testing 259,

tests

Aeroplanes ....8, 44, 71, 72. 78. 84 261.

A. E. G

Aeromarine ] .*

Ago .43

Albatros 44, 286. 288.

Antoinette

Anzani " '2*2*8'

Armstrong- With worth . . .

A. R. or A. L. O '/.'.'.'."'

Aviatik '[[

Avro ..!!!!..!!!!*

Berckmans Scout !!'.!!

Breese "Penguin" . . . . .

greguet 15, 28, 120,' 148,' 288.

Bristol

Burgess

Burgess-Dunne 207

Caproni • • • • ^^g'

Caudron.15, 42, 60. 73,*i66. 139, '220'

Continental Pusher

gurtisa 205, 207. 291.

Curtis tractor

De Haviland .283

Deperdussin ..'.

Dorand 15

Parman 15, 16, 42, 93* ' i2i,"2*28 '

F. E

go^^ker .■..■.'*.".■.■.'.' .' .*43.' 284.

French

French, Letort

^*^^™a» '.'..'.'.'.'.'.8q',93'.

Gotha

Goupy '..'...'..

Halberstadt .43

Handley Page .'ie " 276

Lawsou "M. T. I."

Letorc "iV

L. V. G ^^'

L. W. F '.'.'. '.'.'. '.'.'.'.]'.

Moineau

Martinside !!!.!!!!..!![

Morane-Borel '.'..'.........

Morane monoplane . .

Morane-Saulnier '28Q

Nieuport 45, m, 228.

Ordnance Engineering ....

Paul Schmidt

Paulhan "..,*'

Pierce Sport Tractor

Pilot Observer . . . .

Pomilio aeroplane 1 o

R. E. P. ..: ...'.'..■.'..

Roland 43'

Rumpler 44]

Salmson-Morineau

Savary '

Sopwith [\ 42, 118

Spad 41, 44, 122^

Standard

Sturtevant

Taube [\\[

Thomas Morse

United Eastern

Vickers

Voisin 15, 228.

Wittemann-Lewis

Wright 204. 207,

Zodiac

Aero raids on England

Aero range finder

Aero searchlight

Aero-Squadron

Aerostatic Section, U. S. Army

Agassiz Geological Museum

Ago

Ailerons

Air compass

Aircraft Board

guns

performances, measuring

Production Board 201. 214, 217.

productions

reconnaissance

wireless 138.

Air duels 53,

fan driven pumps

lines

navigation

offensive

pockets

pressure gauges

Air raids, list of

scout

speed indicator or meter

293

Akron. 0.. Goodyear School 156

128 Alaskan jiea jacket 196

121 AlbatrOB 285, 286, 288

267 Allen, P. A 282

266 Allen, F. H 217

274 Allen, James 225

288 Allies 91

291 aerodromes 125

286 aeroplanes 93

294 aviators 90

228 balloons 157

244 raids, long distance , 18

285 wireless 141

288 wireless sets 146

285 Alps, crossing by aeroplane 6

284 Alternator 143, 146, 148

292 Altimeter 24, 126

292 Altitude photographs 108

284 Aluminum-caustic soda process 174

286 Aluminum-potassium cyanide process.... 177

207 America 186

292 aviators 93

289 "Blimp" 156, 157

285 competition 228

291 crankcases 257

292 manufacturers of hydrogen 175

183 training machines 212

287 Anchors and ropes 158

228 Anemoters 165, 270. 273

42 Aneroid 259, 262, 263

287 Angle of attack 252, 254

283 Anti-aircraft batteries 93

290 guns 86, 114, 125

125 post 177

49 Antoinette 228

129 Appendix 158

289 Appendix line 158

228 Appendix ring 158

286 Application of aircraft 238

289 Archdeacon, Earnest 226

292 Arc, potential 150

288 Arkansas .: 210

287 Armatures 146

291 Armed photographic planes 54

15 Armstrong- Withworth plane 285

286 Army, U. S. aeronautics 204

228 Air Service 180, 181, 182

288 aviation field 212

288 Aviation school 212

284 aviation school training 185

291 aviation students 180

285 balloon school 167

228 Deficiency Bill 208

292 Arnold, Bion J 201

119 Arnold, Lieut. H. H 204

44 Artillery 81

228 bombardment 122

283 fire 71. 74

288 fire by wireless 141, 149

287 flre, directing 72, 160

228 regulation 269

283 Ascensional forces, table 162

288 Ascensions 83

292 Astor, Vincent 201

292 Astra 228

130 Astra Wright 228

292 Atlantic Aeroplane 236, 242

291 Atmospheric conditions 165

284 Atmospheric density 259, 266

290 Atmospheric pressure .' 260

onl -Austria n. m. 157

292 Austrian armies 112

228 Austrian bases 241

20 Automatic ball float valve 242

31 Automatic pilot 25, 27, 269, 270, 272

128 Automobile windlass 82

208 Division signal corps 179

163 Aviatik 293

105 Aviation beacons 14

286 field. College Park 207

262 mechanicians 193, 195

272 mechanics, insignia 190

219 officers 195

39 officer's insignia 195

259 School, Army 212

219 School, Curtiss 204

218 School of Military Aerostatics (Ground '

116 schools) 182

139 Massachusetts Institute of Technology,

55 Boston 182

249 Cornell University, Ithaca, N Y 182

200 Ohio State University. Columbus, O. . . 182

197 University of Illinois, Urbana, 111. . . 182

58 Texas University. Austin 182

250 University of California. Berkeley.... 183
249 Georgia University, Institute of Tech-

1= nologj-, Atlanta 188

111 Section, Signal Corps

24 93, 180. 194, 195, 206, 207, 218

294

INDEX

Section, Signal Corps — Continued

Section, Signal Corps, uniforms 190

Aviation. Training ramp 182

Belleville, HI,, oi>eratinK 182

Fairfield, O. (Wilbur Wright Field) oper-
ating 182

Port Sin. Okla,, advanced 182

Hineola. N. Y., oi>erating 182

Mt. Clements. Mich. (Selfridge Field)

operating 182

Rantonl. 111. (Chanute Field) 0|>erating 182

Rock.v Mountain Reserve 182

San Antonio. Texas, operating 182

San Diego. Cal.. operating 182

So. Mississippi Valley. Under investi-
gation 182

Aviation students 187

Aviator. AUied 90. 91

Aviators. American 93. 282

certificates 186. 187

face masks 191

glovea 191. 192

messengers 19.5

service 192. 194

nniforms 195

Avion. Clement Ader's 240

Avro aeroplane 15, 298

Back pressure 251

Bagnell. Lieut. Edward 211

Bairn, Chief mechanic 211

Baker, George F. Jr 201

Baker. Secretar>- of War 298

Balance of jKiwer 3

Balancing free balloons t 163

Baldwin. Ca|>tain Thomas S 204

Baldwin dirigible 205

Balkan Mountains 17

Ballast, sacks 83

BaOoons 83. 84. 157. 159. 163

ballast 163

ears 164

capacit}- 161

captive 74. 75, 81. 85

Caquot 81. 160

companies 160

dirigible pilot certificates 187

Division 179

envelope 158. 164

equator 158

fabrics 164

historic Ill, 112

inflation 82

kite 76, 81. 83. 84. 87. 96, 157

maneuver 88

nurse 86. 160

observation 84. 96. 156

school. Fort Omaha 161. 167, 213

Bamberger, Lieut. R. S 204

Barometer 157

Barrage fire 70

Bartlett, Capt. Robert A 201

Baruch. Bernard II 201. 214

Batchelder, A. G 201

Battery, hydrogen cylinders 171

Battleplanes 39

B. K. (Bleriot Kx|>erimeutal) 284

Beachy air ships 157

Beacon, aerial 133

B«a«on, electric flashlight 136

Beacons, ilermamt' 130

Beck, Lieut. Paul W 204

Belgian cities 25

Belgium, invasion 240, 241

Bellanger, Capt 234

Belmont, August 201

Bennett. James Gordon 201

Benoist Aircraft Co. 242

Berlin 25

Best, E. C 210

Betbenods high frequency generator. . . . 143

Bethenods resonance alternator 143

Boveoa, K. J 211

Biiishaiii, Prof. Uiram 215

Bishop, Oourtland F 201

Blades, variable pitch propeller . . . .254, 255

Bliriol, Louis 226

"Blimp" 157

American 156, 161

BriUah 173, 177

Ooodyesr 176

BUsa, Un. WiUUm H 209, 211

Board of Governors, Aero Club of America 234

Board of Ordnance and Fortification. .222. 223

Body resistance 275

Boring Airplane Oo. 242

Boelke, CaiiMin 64, 66, 93, 241

Borer, F. Jr 210. 211

Boilinf. Capt. Raynal 0 20S, 210, 211

Bomb 87

Barlow 87

daacription 22

dropping 26. SI, 289. 278

lalliog enrves 86

iDiUal vrlocitr 85

releaaiog drvlc* 86

•t*!"!* 22, 278

■ ■■iliardlng maebioaa 64

Boabardment 70, 269, 371, 273

Boabardmant, French 70

Bombing 122

attacks 9

enemy bases 4

night raids 125

parties 125

raids, list of 18

raids, long distance 17

damage done 20

incendiary 20, 34

types of 22. 31

Bond. Brig. General John 0 212

Bonvalot, Gabriel 232

Boots, rubber wading 193

Bowen. Lieut. T. S 208

Brake horse power 255

Brake, for landing 251

Breeches, winter motorcycle 193

Breese Penguin 300

Brequet aeroplane 292, 298

BrequetMichelin war plane 21

Bright, British authority 132

Bristol, Capt. Mark L 201

Bristol Scout Aero]>lunc 292

British aero photographs 93

British aeroplane. Vickers pusher biplane 58

airship 107

armies 171

army tests 239

blimps 173

Commission in U. S 217

De Haviland scout biplane 58

flying corps 217

forces 91

General staff sg

Government 241

Government specification, wireless 145

funs 82

Naval Air Service, instruments 24

Royal Navy Air Service 76. 104

War Office 239

Wright Co 263

Brush discharge 145

Buc, France 230

Buffalo Aero Squadron 210

Buffalo, N. y 210

Bulkheads 248

Bullets vs. high exjilosive shells 51

Bureau of Construction and Repair 214

13urgcss aerojilanc 207, 244

Burgess Dunne aeroplane 207

Burgess, Dr, G. K 213

Burgess, W^ Starlmg 201

Burns, K. J 210

Byrd, Lieut. D. B 211

Cable, A. G 214

Cabot, Godfrey L 201

Coffyn, Capt. Frank T 215

Calcium chloride 169

Calibration tests 267, 268

California Aviation School 213

Camera 91, 106, 107. 117. 264

care of 97

construction 104

Eastman aero 102

Pabbri 103

Howorth 102

long focus 102

stereoscopic 102

types of 105

Camouflage 113

Camshaft 257

Canadian photographer 96

Chauning, J. I'arki: 201

Canton, Brigadier General F. M 211

Cauton-Unne 228

Capacity tanks 230

Caproui planes 12, 13, 50, 241, 278, 295

Caproui triplane 4, 13, 297

Captain de Beauchamp 17

Captain de Kerillis 17

Captive baloons

71, 74, 76, 81, 85, 167, 159. 161

Captive balloons vs, aeroplanes 85

Caquot balloon 78, 81 96, 160

Coquot, Capt 78

Carbcrry, Major Josejih E 201, 208

Carburetor 252

Carburetor headers 250

Carlstroni. Victor , 211

Carlton. Newconib 201

Carolian. Lieut. M 210, 211

Carrizal tragedy 209

Carroll. Capt. P. A 213

Carter. General 204

Cases for a balloon inflation 165

Case for large aeroplane 374

Cartography aeronautic 200

Caudron biplane .16. 42. 73. 139, 285-290-298

Caustic jiotash 170

Ceiling of machine 261

Celoria. Senator 0 203

Central Powers, wirelcaa 141

Centrifugal forces 266

Oertificate. dirigible balloons 187

bydroaeronlanes 188

spherical balloons 187

ChamlMTlain, Senator George E 218

Chamber of Drputies. French 282

Chambers. Capt. W. 1 201

Chandler, Major Charles de F

167, 201. 204, 208, 213

Changes of uniforms J93

Changing speed . . . . 252

Chanute. Octave ' 226

Chapin. Roy D [] 20I

Chapman. Lieut. C. C 208

Chase, Brig.-Gen. John ] . ! ! ! 210

Chicago Training Station ..'.', 213

Chief Aeronautic Engineers 245

Contractor of Navy .['. 219

Inspector Military Aeroplanes . ... .239, 240

Signal Officer

. 181, 202, 213, 219, 223, 224, 225

Cnristofferson 244

Chrome vanadium steel ] 250

Circuit of Eastern Prance ' 232

Clark. Capt. V. E 245

Clerget motor 228

Climbing ; ; ; 253

Clinometer 269

Close formation flying 115

Close reconnaissance m

Coast artillery 71. 194

Coast defence .' igg

Coast defence, function of aircraft 7

Coast guard 237

Coats, aviator, antisinking 190

Coats, aviator, leather 194

Cochran. Alex. Smith 201

Coffin. Howard E 201. 214, 215, 217

College Park. Md 204. 205, 207, 208, 209

Collier, Robert J 201, 204. 206. 212

Colonia Dubliin m

Colorado 210

Color filters 99

Colt 49

Columbus, N. M 208, 209, 210, 213

Combat machines, tactics 54

Commissioned personnel 161

Committee on Aeronautic Maps and Land-
ing Places 199, 201

Committee on Military Affairs 213

Committee of National Aviation 233

Communication by Wireless 139

Compass 24

Comjiass bearings 117

Conant, W. M 210

Concealment 116

Concentrating rings 158

Condenser charging device 149, 150

Condensers, wireless 145, 146

Conger. Roy U 201

Cougress, Acts of 206, 206, 222, 237

Connecticut 210

Connecticut Coast Artillery 210

Continental Pusher 291

Construction of aeroplanes 245

Construction of balloons 163

Contact patrol 4. 112, 121

Contact patrol machines 122

Contest Committee, Aero Club of America 187

Coolidge, T. Jefferson 209

Cooling system 257

Cooperation between balloon and artillery 77
Council of National Defense 215, 235. 237, 248

Coutelle 178

Coyle, Lieut. Arthur J 211

Craig, A. M 211

Crankshaft bearings 257

Culver, Major C. C 140, 201

Culver radio apparatus 140

Culver wireless set 146, 164

Cummings, Lieut 210

Ourtiss aeroplane . . . .204, 207, 236, 244, 300
Curtiss Aviation School . . . .204, 210. 211, 212

Curtiss, Glenn H 201. 207. 222

Curtiss JN. 4-B tractor model 291

Curtiss triplane 12, 44. 291

Curtiss Wireless Scout 44

Curves of stress 256

Dansette 228

Dardanelles 91

Dargue. Lieut. Herbert 76

D'Arsonval 177

Daucort, Lieut 17

Davis, Commander Cleland 201

Davis, Driggs 60

Davison, Lieut. F. Trubee 201

Day signalling 71

Dayton. Ohio 826

Dayton Wright Co 244

Decarburatiou of oils 378

Deeds. Lieut. Col. E. A 301, 214

Defensive line 70

Deficiency Bill 218

De Havilland 288-287

Delivering aeroplanes to Europe 246

Density 269, 280

Density of gases 368

Density tables 868

Department of Arronautios 817, 319

Deaigner 859

Designs and tests of suspension patohea. . 164

Deatrnotivrnrs* of proleetUes 40

Detached flight 118

Dick. P. R 310. 311

Dickson, Charles tOl

INDEX

295

. .302

Dickinson, Lieut. Oliver P. .

Die-forging

Dielectric constants

Diffln, F. O

Directing artillery flr^e ^^- ^^i isi: li^.
Dirigibles 125, 157, 158,

Baldwin

i>ilot's certificate

first U. S

military

naval

wireless

Distance reconnaissance

District of Columbia

Dive attack ■ ■ •

Dodii. Capt. T. F 208.

Dodge, W. Earl

Dope, inflammable

Drag

Drag roping

Drift

Drift coefficient

Drift indicator

Dropping bombs

Dubilier condenser

Dubilier system ■ ■ •

Dubilier, William l**"-

Dugouts, German

Dumont, Alberto Santos

Duesenberg motor

Dusseldorf

Duties of balloon personnel • ■ ■•

Dwyer, J. T 210.

204
250
146
213

160
165
205
187
204
157
157
143
111
219

65
245
202

72
275
163
117
275
272

22
145
137
253

70
202
242
7
164
211

First aero appropriation — Contintted

dirigibilo 204

«i«ht 222

gunplane *•'''

militar.v aero review

230

Eastman aero camera

Economical speeds

Effect of size on performance

Effect of size on structural weight

Electric flashlight beacon

Electric headlights

Electrical Review

Electrolyzers

Electrolyzers, American

Electrolytic method

Electrolytic plant • •

Electro magnetic controlled oscillator ....

Ellis, Brig. Gen. H. Handy

Elongated balloons ol-

Emergency Air Fleet

Enemv aircraft • •

England I''"'

England, Brig. Gen. Lloyd

England, night flying in

English wireless apparatus

Enlisted aviators, insignia

Enlisted men. Aviation section

Begular Army

uniforms

Enlisted personnel

Enlisted Reserve

Enlisted Reserve Proper

Equipment, balloons companies

Equipment, cost of

Ericson, P. G i' .V

Essen T, 10,

Etampes • • ■ • • • ' •

European War -^^i. -*=>•

Evans, Gen. Robert K

Evolution of military aeroplane

Expansion of hydrogen .... ■

Experiments at South Foreland

Expert Aviator certificate

102
254
279
279
136
25
177
170
171
170
171
l.'Jl
210
159

11
160
259
210
127
140
190
193
181
195
161
1«1
181
164
213
213

27
287
259
202
204
168
133
189

Pabbri photo apparatus ■ ■ . ■ •

Face masks for aviators 191. 1«''.

Factors of air supremacy

Factors of safety • • • •

P. A. I. Certificates 18"-

F. A. I. rules

Pall of shots

Pan driven generator • • • . ■ ■ •

Farman, Henri. 15. 16. 93, 222. 282. 287.

Parman biplane

Parman reconnaissance biplane .... ■ • ■ ■

Favre. A. L : ...... .210,

Federal Reserve Officers' Training Camps . .

Federal service

Ferber, Cajrt. Louis

Ferro-silicon • • •

Fiat motors '■^•

Fibre stress

Field artillery

Field artillery control

Field companies

Field compression outfits

Field generators

Field generators, hydrogen

Fifth arm ; , ■ ■ ■ ■■■

Fighting in the air 57. .2bH.

Fighting machines

Fighting pilots

Fighting tactics .

Filling hydrogen cylinders

Filling kite balloons

Films vs. plates

Fire control

Fire safety device

First aero appropriation iiA'Vi'i'

Aero squadron ^i"> ^^^

requisition

222

specifications ^^^

spotting artillery fire JjJ

tractor bijdane. U. S 2-7

use of aeroplane in war -^9

Piske, Rear Admiral Bradlej A 202

PiUgerald, Capt. S. \V 215

Fixed blade propeller 253, 255

Fixed camber wings 252

Flare lighting Ijf

Flares Ig"

Flare up "°

Flashlight beacon i^o

Plexilile pijiing ^"1

Flight commanders 11^

Flint Aircraft Mfg. Co ^**

Floats, metal ^gi

Flying Corps ^»^

instruments iJJ

level 261

^r. ;.;.• .•.•.;.■.•;.• .■.•.■.■;.;;i9i,ib4; 195

suit, summer i^^

Fokker. batteries • ■ . • • ■ • • »'

Pokker nionoi)lane 241. 286, ^'^^)

Folding landing gear 251

Folding, packiug, shipping balloons lOd

Forces of gases 1°^

Formation, aerial fighting Oi

flying, lamp signals 68

flying, rules ^»

opposing {|^

reconnaissance • Jip

Form of application. Officers Corps 180

1^ Syr'". ■.::::■.■.:■.:• 264; •205.- 22^ 225

Port Omaha 161. 167. 169. 170

Port Sam Houston • . • • • f"8

Foulois. Benjamin . . 194. 204, 206, 208. 225

French aerial beacon 133

Aero Club 202

aeroplane ^^j?

air raids f"

air raids with British i»

Army 230

artillery ^0

aviation '";

aviation camp ^^"

aviators j"

balloons . 'Ij:

bombardment •';

bombing plane ;>}

French cameras zi

dirigible • ■ ■ • l|?^

Flying Corps 185. •i"''

front \l\

government *^^

kite balloon g*

landing system ■ ■ • 1^»

Military competition ^^0. ^o"

Ministry of War ^27. iii

nightflying

observers

127
105
128

German armed machines 47

Automobile Constructor's Ass 231

aviation beacons 130

bases SI

biplane, A. E. 0 42

cities 25

combat machines 43

costly failure 240

defensive line 70

dugouts 70

government wireless 154

hydrogen making 171

hydrogen trucks 172

naval bases 27

positions 70

Roland jilane 46

Rumpler plane .... 44

Scout 97

Spad 45

Taube 154

trenches 70

War Department 231

German wireless apparatus 140, 141

communication 154

stations 152

Gillmore, R. J 211

Gliding angle 229

Gloves for aviators, summer 192

Gloves for aviators, winter 191

Gnome 228

Godfrey. Dr. Hollis 214

Goerz range finder 31, 32. 33

Goerz sighting telescope 31

Goethals, Maj. Gen 21'7

Goggles ... 192, 193, 194

Gompers, Samuel < 214

Goodrich, C. C 161. 210. 211

Goodyear Blimp 175

Goodyear School. Akron, Ohio 156

Gorrell, Lieut. E. S 208

Gotha 14. 289

Gotha battleplane 79

Gotha biplanes 3

Gotha biplane, fusilage 59

Gotha gunners 79

Graduate School of Military Aeronautics. . 185

Graham. Lieut. Harry 204.208

Graig, AM 210

Gravity service tanks 240

Great Britain's Dirigibles 157

Ground cloth °|

Ground School of Military Aeronautics. . . . 183

Ground signal sheets 121

Guerilla tactics 115

Guide and anchor rofie toggle 158

Guide rope lo3

Guillaume. Trench 5

Gunners, aero 71

Guns, largo caliber 72

Itewis 1^9

mounting on aeroplanes 67

mounts 54

Vickers 73

Guynemer, Capt 31

Gyroscope efforts 247

Gyro manual control 26, - /3

Gyroscopic moments 256

Gyroscopic unit 269. 271

pilots

scout «'

trenches

107

103
194
40
46
204
164
160
154
295
55
121
211
182
211
226
176
288
256
71
245
194
165
160
165
63
270
286
64
58
174
164
108
245
251
221
257

War Deiiartment 226

wireless aii|)aratus 1*0

wireless trucks 144

wireless set 14]J

Franco Prussian War 221

Free balloons

163

Free balloon training 161. 163

Frost, Cori>. B. C ^10

Frost, D. O jll

Fuel capacity ^*;?

Fuel leads 2j0

Fuel supply

Pull loads 254

Funston. Gen ^"g

Fuselage ■ ■'°%

Fuselage of aeroplane "o

Gallaudet Aircraft Corp 244

Garrison uniforms 195

Garros. Roland „%l

Gary. Elbert H 202

Gas beacon 1^°

Gas cylinders " '

Gasoline supply J*J

Gasoline supiily system ^4»

Geiger, Lieut, Harold 206

General Aeronautic maps J97

General aeroplane , ,■ '. Tco

Generation and compression of hydrogen . . 10^

Generator -69

Generator, wireless 1* '

Geographical Congress 201

Se?mi"ny ■::::: ; : : ; : : .'8i.' i^iVHo: Vie. 233

German aerial beacon ■•■ t-?"

aero camera l"l' i"^

aerodromes at night ••■■■■• J^ ak' oV log

aeroplanes 57. 79, HO, ad. i-»

German ammunition 5 /

Hagerty, Corp. E. B 210,

Halberstadt

Hall, Brig.-Gen. P. L

Hall, E. S

Hammond, John Hays

Hand air pressure i)umps

Hand control lever 269. 270.

HandleyPage warplane. .12, 47, 274, 276.

Handley, Sergent Harrison

Hangars

Hangars, illumination

Handling captive balloon windlass

Haunay, Maj. D. R

Hare, James H

Harriman, W. Averill ■ ■

Hawley, Alan R 101, 202, 216, 217,

Hawley. William

Heavier than air machines

Heinrich Corp

Helicopters • ■

Heligoland • -7.

Helmets, aviator s -Im^-

Hennessey. Capt. Frederick B 204.

Henrj. P. J 210,

Herbert and Husgen 100,

Herck, Capt J

Hertz wireless experiments

Hickman, Willis G

High explosive shells

Hindenburg statue • . . •

History of aeronautics 20b,

History of U. S. Army aeronautics. . . .204.

Homogeneous dielectrics

Honig, Edgar 131.

Honig circles

Hood

Hoppin, F, L. V

Horizontal reference

Horizontal surfaces

Hotchkiss, Gen

211
286
210
219
202
249
272
287
211
209
127
164

77
206
202
243
202
223
244
226

25
193
206
211
106
213
141
211

51
156
211
219
146
210
131
193
211
272
247
49

296

INDEX

Hough, Brig. Gen. W. B 211

House Committee on Military Affairs .... 214

Howard. Brig. Gen. C. W 211

HoweU, W. T. 210. 211

Howitzers 71

Hoyer. Lieut. R. H 211

Hobbard. J. P 210. 211

Hulbert, Congressman Murray 219. 243

Humphreys. Lieut. Frederick E 204

Hutchings, Brig. Gen. H 211

Hydraulic tests of gas cylinders 163

Hydroaeroplane pilot's certificate 188

Hydrogen 84

American manufacturers 175

carriers 169

eylinders 160

field generators 176

for military purposes 167

from water gas 176

portable gas j>lant 170

Silicol process 171

supply 160

trucks, German 172

Hydrogenite 176

Hydolite 175

Immelmann, Lieut 65, 66. 241

Imperial Aero Club 231

Imperial Automobile Club 231

Improvements in design 257

Incendiary bombs 20

Incendiary rockets 159

Inclinometer 24, 126

Identification badge . 196

Indenting for stores 97

Independent interrupter 142

Induction coil 142

Inflammable doi>e 72

Inflation of balloons 82. 163

Insignia 190. 199

Insignia, sleeve 193

Inspection, balloon envelope and net 164

Inspection window 158

Installation, wireless 138

Instructions for aero photography 91. 109

Instructional aeroplanes 240

Instruments 14, 23, 24. 126

Instruments, sighting telescope 31

International Aeronautic Federation. .186, 201
International Aircraft Standardization

Committee 213

International Convention on Aeronautic

Cartography 200

International Geographical Congress 201

Invisibility of aeroplanes 125

Iron contact process 172

Isotta Fraschini motors 12, 13

Italian Aeronautic Topography 203

aeroplanes 157

airscout 229

Commission on Aeronautics in U. S. . . 10

raids 19

theatre of war 19

Turkish War 232

Italians 241

Italy, aeronautic map 202

Janney Aircraft Co 244

Jenkins. W. C 210. 211

Johannistal beacon 136

Johnson, Corp. Greenhow 212

Johnson. W. J 210. 211

Joint Army and Navy Committee 204

Joy. Henry B ; 202

Junior MiliUrj' Aviators ..179. 186. 192, 194

Junior Military Aviator's insignia 190

Junior Squadron 183

Junior \N ing. instruction 184

Kaiser's prise 230

Karlshrnhe raid 17

KeBey. O. E. M 204

Kentucky « 210

Kid 7. 10. 25. 27. 29

Kiel Canal 18. 25

Kiel, raid on 30

Kilmer. Lieut. W. G 208. 215

Kinematograph , 96

King and Queen of England 47

Kirtland. Lieut. R. Carrtngton 204

Kite balloon 71. 77. 81

83. 84, 85. 87. 91, 06. 157. 163, 164

Canadian 88

eompany 83

steering bags 164

truck 169

unit 82

Kit* obaerrer 99

Kitty Hawk 226

Klaxon horn 121

KnowUon. R. J 210. 211

Kodja Chai 91

Kolbasa 86

Konaot. W, W. Jr 211

Kruaa, Berj. E. A 210. 211

Laffoo. Lieut. 66

Lahm. Maj Frank Vurdy 76. 202. 204, 205

Laird Aviation Co. 244

Laml>prt, Capt. A. B 202

Lallemand, ChAries 208

Lamp signals, formation flying 56

Landing brakes 251

gear 251

ground 127. 132

places 198. 199

spots for balloons 163

stations 127

Langley. C. P 222. 223. 226

Langley Aerodrome 223

Langley Field 173

Lanzuis Aircraft Co 244

Large aeroplane, case of 274

Large warplanes 2-41

Large Zeppelin apparatus 138

Law, Ruth 25

Lawson "M T-1" 292

Leading American aeroplane 244

Lebaudy dirigible 157

Lefrance, Jean-Abel 31

Le Large, Capt 172

Leggins 193

Lenses 104

Letord 15. 288

Levant air raids 20

Lewis gun 48, 52, 61, 72, 139, 208

Life Saving Service 237

Lift coefficient 275

Lighthouses, aerial 134

Lighting aerodromes 127

Lighting equipment for aeroplanes 133

Light scout aeroplanes 240

Lighting stand 131

Lights for landing grounds 132

Liquid pressure gauge 261

Line of direction 102

Line of reconnaissance Ill

Literary Digest 131

Local strength 279

Local or artilh'ry reconnaissance 112

Lockhart, Henry, Jr 202

Logj- 247

London 126

London Aeronautics 127

Long distance flights 187

Lend distance raids 125

Long Island Map 200

Lovett, Lieut. Robert A 202

L-section . 250

Ludwigshafen raid 17

L. W. F. aeroplane ■ 271

L. W. F. Engineering Co 244

L. V. G 287

Machine guns, mounting 67

Magnetic forces, wireless 151

Magnetos 257

Major aerial operations 241

Mann, Congressman James R 213

Manoeuvering and pressure valves 164

Manoeuvering valve 163

Map holder, Sperry 201

Maps 74. 75, 91, 113, 197

Map with photograph of route 200

Marconi Co., wireless 155

Marconi wireless experiments 141

Mariner's chart 197

Martin aeroplane 207

Martin, Dr. Franklin 214

Martinside 286

Massachusetts Institute of Technology .... 216

Maurice Farman biplane, wireless 147

Mauser Work.s, Oberndorf IS

Maximotor 244

Maxim, Sir Hiram 48. 222

McClasky, Lieut. J. W 204

McCormick. E 210

McCormick. Harold F 202

McCoy, Capt. J. C 202

McDaniels, Lieut. Curry A 211

McGregor, J. S 213

McMillin, Capt. Ralph E 210

McMillin, Emerson 202, 209, 232

McMullen. Lieut. Byron 211

Mean density 260

Mean pressure 260

Mean temperature 260

Measuring aircraft performances 259

Mechanical interrupters 150

Mechanics of the aeroplane 238

Mercedes engines 3, 288

Merrica, P. D 213

Messengers, motorcycle 194

Messerschmitt. A 173

Metal construction for aeroplanes 250

Metal floats 251

Meteorology 166

Mexican campaign 206. 208, 231

Mexico, punitive expedition Ill

Mexican War 204

Meyers, Eugene. Jr 202

M. F. P. Aero Co 244

Micbelln. M 47

Mignot, Lieut. M 213

Military aeroplanes 245. 240. 257

afroplanes, evolution 222

aerodromes 106, 135

arroKtntics 157

aviftlors 179. 1»2. 194

aviator's insignia 190

dirigibles 167

loa<f 246

Military aeroplanes — Continued O

Qiaps 197

observation balloons 158

Military operations .91, 197

operations with aircraft 5

service 157

seaplane supply system 249

Miller, Capt. James E 202. 214

MiUerand, M 233

Millevoye. M 233

Milling, Lieut. T. de Witt 204. 208

Mineola, Long Island 216, 211. 215

Minnesota 210

Moineau 47

Monastir, photo 22

Monoplane, Morane 287

Montariol. Lieut 185

Montgomery, R. L 214, 215

Morane-Saulnier 207, 241, 286-287-288

More. Morgan 211

Morse code 77, 121, 128. 134

Morse, D. P 210, 211

Motion picture films 108

Motor Boating 29

Motor, Baerdinorear or Clerget 43

Competition, Kaiser's 230

Motor, Canton-UnnS 39

car wireless station 138

Isotta Fraschini 50

Servo 269. 270

transports 169

trucks 160

truck operation 164

Fiat 12

Rolls-Royce 274

(See Textbook of Naval Aeronautics).

Mouillard 226

Mount Cornillet 91

Mufflers, aviator'.s 195

Muffler requirements 251

Mulock, Lieut. R. H 134

Multiplane 222

Munich raid 18

Mustin, Lieut. Commander Henry C 202

Muzzle velocity 52

Nash, Brig.-Gen. Van Holt 210

National Advisory Committee on Aeronau-
tics 214

Aerial Coast Patrol Commission 245

Aeroplane Fund 235

Guard of New York 209. 213

Naval dirigibles (See Textbook, Naval Aero-
nautics ) .

maps 197

observers 91

Navarre, Lieut 64. 241

Navigating instruments (See Textbook,

Naval Aeronautics) 126

Navigation lights 25

Navy Department 204

Navy Department, Pensacola 173

Nebraska 210

Net toggles 158

New Hampshire 211

Newport News, Virginia 210

Newton, Byron R 236

New York 210

New York National Guard 209

New York to Albany map 198

New York to Chicago map 199

New York to Newport News map 199

New York to San Francisco map 199, 200

New York World 212, 236

Nieuport aeroplane 4. 7, 121. 284

Night bombing 21. 23

flying ..25, 73, 125, 127, 130, 131. 133. 272

landings 126. 128. 135

landing sights 24

lights 132

patrol 125

operation of aeroplanes 126

raids 10, 125

signalling 71, 132

use of balloons 159

Nocturnal flyers 130

Non-recoil gun mounts 64

Normal atmosphere 261

Norris, G. L 213

North Carolina 211

North Pole 200

North Sea 136

Noyes, Corp. D. R 210

Nurse, balloon 86

Observation balloons 86» 06, 156. 157. 158. 160

"Observe for line" 75

"Observe for range" 76

Observed air B))eed 266

Observer, wireless 147

Observer, wircleas signaling ■ . . 149

Observers 71. 72. 74. 84. 87. 91.

99. 113. 114. 116, UH. 119. 122. 126

Odell, Quartermaster Serj. W. T 210, 211

Offensive, fighting tacticM 68

Officers* Reserve Conw. form of applica-
tion 180

Oil consumption S80

OUIng system 867

Ohio .: 211

Oklahoma 211

INDEX

297

Olyphant. R. M. Jr 210. 211

Omaha 163, 204

One-place machiniw 246

Operation of balloons 213

Opposing formation 115

Orders of reconnaissance 116

Ordnance Engineering 291

Oregon 211

Organization and Training Division 182

Organization of balloon companies 164

Osborn. Lieut. B 210

Oscillation 247

Oscillating circuits 141, 145. 149. 1.51

Ostend 7. 27. 91

Oversea reconnaissance 246

Pallone-Cervo Volante 85

Palmer. George M 210

Pan Americanism 222. 237

Pan American Aeronautic Exposition .... 222

Paper kites 159

Parabellum gun 48

Parachute 87, 88

Parasite resistance 245

Paris 125, 241. 282

Aero Show 232

•Madrid Race 232

■Rome Race 232

siege Ill

Parke. J. D 202

Patrolling aeroplanes 110. 125

Paul Schmitt 285

Payne, S. G 213

Peary, Rear Admiral Robert E

201. -'IT. 238, 239

Pedals 270

Pendulums 272

Pensacola 173

Performance curves 252. 253. 254

Perfetti, Maj. R 10. 11

Perkins, George W . . 202

Permanent air routes 197. 199

Permeability of gases 164

Parmelee. P. 0 204. 206

Pershing. Gen. John .J 111. 128. 20K. 209

Personnel Division. U. S. Signal Corps... 180

Persuit or combat machines 43

Petit Journal 233

Petit Parisian 233

Petrol consumj}tion 264

Petrol flares 127, 133

Peugeot 47

Philippines 204

Photographic Corps 93

machines 4

maps 91. 200

maps of sectors 198

positions 105

Photographing enemy positions 4

Photography 91

aero 198

altitude 108

balloon 164

Pilot 117. 130. 270, 280

balloon 158

certificate 204

certificate, spherical balloon.s 187

hydroaeroplane 187

cockpit 240

observer 269

Pilot signals 129

Sperry automatic 269

Pistol camera 101

Plates vs. films 109

PlessisBelleville 66

Pomilio, Capt. A 213

Roncagli. Commander Giovanni 203

Poor, Prof. Charles L 202

Portable aerial beacon 133

field generators 160

gas beacon 133

hydrogen gas plant 170

wireless sets 140

Position 41

Position of aeroplane guns 68

Post, Augustus 63, 81, 217

Potomac River 222

Powerplant 245

Preliminary flying test, U. S. Army 189

Preliminary Training Tractor 242

Prentice. W. F 213

President Manuel Estrada, of Guatemala . 201

President Wilson 214, 218. 219. 230

Primary Military Tractor 244

Prince Henry of Prussia 230, 232

Prince, Lieut. 217

Prince. Norman 241

Principles of aerial combat 63

Problems in aeroplane construction 245

Problems in aerophotography 91

Propellers, fixed blade 253. 255

for variable pitch angle 253, 255

stresses 255

variable pitch 253

Properties of hydrogen 167

Property damages from balloons 164

Protecting aeroplanes 121

Protecting reconnaissance machines 115

Pulitzer. Ralph 202. 212

Purifying hydrogen 169

Pursuit machines 40. 246

Pushers 247

Quartermaster Corps 194

Rader, Lieut. Ira D 208

Radian 256

R. A. F 260, 277

Raiding 39

Raids 79

maps 197

night 125

Zeppelin 125

Radio Communication 139

Division. U. S. Navy 155

engineers 148

for aeroplanes 139

frequencies 152

set. Washington 154

Radius of action 253

Railway truck for hydrogen 174

Reber, Maj. Samuel 202, 204

Receiving station, wireless 151

Receiving trucks, wireless 144

Reconnaissance Ill, 112, 245, 269

aeroplane 240

machines 115, 121

patrol 114

Reconnoitering 4

Red sack for rippingjianel cord 158

Reed, Lieut. Charles 215

Reference plane 269

Regular air lines 200

Regular Army 179. 180. 186

Regulating artillery fire 271

Regulation for uiiiform.s of U. ,S. Aero-
nautic personnel 190, 193

Relief map 179

Renault motor 15, 222

Rej)resentativo American aeroplanes 244

Reserve Military Aviators 179, 186

Reserve Officers' Aviation Section. Signal

Coriis 214

Reserve Officers (flying duty) 181

Reserve Officers (non-flying duty) 181

Resistance 247

Reverse bending 256

Revolving commutators 152

Reynolds, C. H 210, 211, 234

Ribel, Oscar 63

Reid, Ogden Mills 202

Rigging truck 82

R. M. A. certificates 189

Rip panels 163. 264

Roberts motor 244

Robinson motor 244

Rockwell. W. L 210, 211

Rogan, Brig. Gen. C. li 211

Rogers, A. B 213

Roland 283

Rolls-Royce motors 288

Roseuwald. Julius 214

Rotation in pitch 256

Rouzet 146

Royal Aircraft Factory 13. 259

Royal Air Service 13. 15

Royal Flying Corps 6, 15. 77. 259

Rubber wading boots 194

Rumpler 47. 288

Russel, R. F 210. 211

Russia 157. 174

Russian air scout 120

balloons 86

machines, Sykorsky 55, 240

Ryan, Thomas F 202

S. A. E 250

Safety device 251

Safety point 92

Sales, Brig. Gen. W. W 212

Salmon. Corp. H. H 210, 211

Salmson-Moinian 287

Salonika 9, 10, 17, 33, 125

San Antonio 204, 208

San Diego 204, 205, 211, 213

San Marsano, Charles de 201

Santos Dumoot, Alberto 226

Sausage 81, 84, 159

Schools, Curtiss aviation 204

of military aeronautics 182

Schuckert generators 171, 172

Scientific American 178

Scott, Gen 202

Seaplane (See Textbook Naval Aeronautics) 248

Searchlights 126, 127, 128, 136. 272

Searchlight signaling 128

Second and Third Aero Squadrons 213

Secretary of Aero Club of America 187

War. U. S 190. 206, 208, 217, 218, 219

Seeing wireless signals 138

Seiberling, Frank A 202

Selfridge, Lieut. E 204

Selfridge Field 224

Semi-rigid dirigibles 157

Senior Squadron 183

Senior Wing, instructions 184

Service cap 195

Servo motor 270, 288

Shapes of balloons 164

Sharp, Ambassador 202

Shaw. Edwin C 202

Sheldon, Lieut. Harold P 212

Sbeppard-Hulbert Bill 217

Sheppard, Senator Morris 219. 243

Sherman. Lieut. William G 204

Shinnecok 244

Shoes, aviator, winter 198

Shooting through iiropelters 68

Short range reconnaissance 246

Shrapnel 71, 72

Sideslips 181

Siege warfare 160

Siemens Bros. Co 171

Signal codes 128

Signal Corps .161, 175, 182. 192. 193. 194

204, 206, 207, 212. 213. 219, 223. 245

Signal Enlisted Reserve 181. 182

Signal Enlisted Reserve Corps 179

Signal Equipment 132

Signaling 71. 72. 77, 80, 86

Signaling by searchlight 128

Signaling to aeroplane 121

Signal Officers' Reserve Corps ...179. 182, 211

Signals at night 133

for night flyers 131

from balloons 160

Silencers 21

Silico Acetylene process 178

Silicol process, hvdrogen 171

Simon. E. J 155

Simmons, Lieut. H. H 215

Shock absorbers for landing gear 251

Shoulder loops 190

Skill in piloting 41

Skill in taking photos 104

Sykorsky 55

Small power wireless sets 140

Smith, P. D 210. 211

Smith. Serg. L. V 210

Sofia 17

Somme. jihoto 5

Sopwith aeroplanes ... .60. 118. 241, 244, 283

Sopwith factories 47

Sorbonne 233

South Foreland experiment 133

Spads aeroplanes 241. 288

Spark electrodes 147

Spark gap 140, 141

Special aeronautic maps 197

Specifications for uniforms 190

Speed 40

Speed course tests 266

Speed indicators 267

Speed in tactics 64

Speed scout 242

Sperry automatic pilot 25. 269, 271

bomb sight 19, 35

Gyroscope Co 155

Lawrence B 25, 199. 202. 210. 269

map holder 201

Speyers, J. R 211

Spherical balloons 81. 158. 159

Spherical balloon pilot's certificate 186

Spirit level lateral inclinometer 24

Spotting aeroplanes 54

Spotting artillery fire 71, 72. 73. 77, 153

Spreading balloon envelopes 163

Squadron commanders 113

Squadron flight 117

Squires. Brig. Gen. George O

202, 204, 205, 206. 209. 214. 215, 217

Stability 239

Stallometer 269

Stamford 210

Standard aeroplane 244-292

Standard aeroplane aerial 146

Standard aero-squadrons 186

Standard atmosphere 261

Standard density 260. 261. 268

Starting field 245

Starting motor for engines 248

Statoscope 158. 262. 263

Steel aluminium alloy 250

Steel battleplane 244

Steel spring shock absorber 251

Steel tractor 244

Steeple banked turn 256

Steinmetz, .Joseph A 217

Stephens, James S 202

Sterling Telephone Co 140

Stevenson, Serg. J. H 210, 211

St. Louis Balloon Race 101

Stockton. P. R 211

Strategical-reconnaissance machines 245

Stream line tank 250

Structural 279

Students, wireless 141

Stupar tractor 144

Sturtevant aeroplane 244, 291, 292

Sulphuric acid 169

Summer flying suit 191

Supply of gasoline 249

Supply guage 251

Supplv tanks 258

Sullivan, J. D 210, 211

Supremacy of the air 39

Swashbaffle plates 248

Synchronized spark gap 146, 147, 148

Table of ascensional forces 162

Tables of density 260

Tactical reconnaissance machines 245

Tactics in air duels 53

298

INDEX

Tail cups 164

T»nk« 247

Tarnt 71, 74. 76, 122

Tsube 130

Taylor. CapL R L 210. 215

Taylor. Rear Admiral David W 214. 215

Technical training, balloons 163

Tehanak. City of 91

Teleiibone car 82

Telephonic communication 159

Tenth Int. Geog. Congress 201. 203

Temperature 260. 263

Tennessee 211

Tension . . 255, 256

Teat cut out 270

Testing aeroplanes 259

Ttating cordage and fabric for balloons . . . 164

Testing Squadron 259. 261. 264

Testa for aviators' certificates 1S6

Testa, wind channels 275

Texms 211

Texas City. Mex 205

Thaw. Lieut. William 211. 241

Thermometers 165

Thermos flask 261

Thomas-Morse 291-292

Thrust 256

TUlottson. Brig. Oen. Lee S 212

Timm Aviation Co 244

Tiraudes *^8

Tiiard, Capt. H P 259

Toronto 216

Toriiedoplane 12

Torpedo attacks 9

Torque 247. 256

Torsion 255

Touring Club of lUly 203

Towers. Lieut. Commander J. H 202

Training aviators for IT. .S. Army 179

Training balloon companies 164

Training fiilds 180, 187

Training Fifld. American 186

Training machines 244

Training machines. American 212

Trajectory 32

Transmission of messages 112

Transmission, wireless 141

Tranfli>ortation. balloons 81

Trenches 70. 71. 75. 90. 105, 159

Trenches. British 130

Trench shelters 70

Trentino Army 6

Trent iuo front 72

Trial flights 224

Trieste Raids 19

TripUine scout "8-3" 244

Triplane. advantages of 45

Tri|>lane. Caproni 278

"Triiie Hound" 13

Tripoli 229

Tropics, uniforms 195

Tubing for fuel leads ... 250

Tulie wagon 84

Tuning vibrator 142

Turkish-German iKwitions 125

Tnrney, George W 202

Turner. K. M 202

Twin motored .J N Tractor 244

Twin motored Handley Page 276

Two engined aeroplanes 239

Two place machines 246

Two propeller system 246

Types of Aeronautic Maiw 197

Ubmt biues 9. 21

TTnifomi* reguUtions 193

Uniforms, specifications 190

Uniforms, U. S. Aeronautic Personnel 190. 193

United Eastern Aero Con 242. 299

United SUtea 7. 170. 173

18S, 11)3. 195. 201, 212, 224. 245. 282

aero maiM 197

•ertmautic p<-rsonnel, regulations for uni

forma 190. 193

aeronautics, history of 204

armed machine* 47

United States — Continued

aviation students 181

dirigibles . 157

Government 223

Government wireless seta 153

Navy Radio Division 154

training of aviators 179

training fields 186

War Department 222

wireless students 141

United States Army 76, 204, 205, 208, 209, 245

Aviation School 210

Balloon Co 169

Balloon School 161, 163

Balloon School, Ft. Omaha 167

biplanes, V. S 140

gasoline supply system 242

Reserve Military aviators test 189

service insignia 190

uniforms 195

University of California 216

Illinois 216

Ohio 216

Texas 216

University students studying aviation .... 181

Use maps and compass with free balloon . 164

Useful load 245

UsueUi, C 203

Valve cord 163

Valve line 258

Vanderbilt, Col. Cornelius 202

Vanderhilt. W. K 202

Variable-camber wing 252

inductance 148

pitch blade 254. 255

pitch propeller 253. 265

pull 128

radiators 252

Varnishing cotton balloons 164

Velocity 247

Velocity of aeroplane 275

Verdun 64. 128

Vermont 212

Verys Light 75. 76. 128

Verys jtistol 73, 76

V formation 30

Vibration 248

Vibration absorbing material 252

Vickers gun 48. 72

Vickers Scout 286

Vienna International Aeronautical Federa-
tion 201

Vilas, L. A 202

Villa's raid 208

Vincent. J. C 219

Virginia 212

Virginia National Guard 212

Visual signal codes for balloons 164

Vitriol process 168

Voisin 32. 47. 222, 228. 269. 290

Voisin Brothers 226

Voisin-Peugeot gun plane 54

Volunteer forces 180

Waldon, Sidney D 214, 215

Walker. J. Bernard 217

Walker. .John C 204

Walvets 64

Wanamaker. Rodman 210

War. decision of 3

War Department 179. 217 245

Wardrop. G. Douglas 202

Wards. Lieut. Forest 210

Ward. T. P 211

War kites 99

War office 229

War with Mexico 204

Washington, Cutting A., radio set 153

Washington, D. C 179

Washington Signal Corps Flying School . . 182

Water gas for hydrogen 176

Watkins, Lieut. B. O . 215

Wave length, wireless 142

Weight saving 279

Wellington, quotation Ill

Wendell, Evert Jansen 237

Western battle front ] 107

Western front 's2, 98

Western theater of war .' 13

West Virginia ' ' 212

Wheeler, Lieut. D. R '.'..'. 215

Wheeler, Monroe ' 202

Wheeler. S. S ,,] 202

White. Brig.-Gen. George H 211

White House 212. 217

Whitney, Harry Payne .' 202

Wilhelmshavcn 7, 10

WiUard. Daniel .' 214

Willets. Lieut. W. P 210. 211. 215

William, I. R _' 230

Williams Aero Co ,'. 244

Willis. Lieut. R. H , . , 208

Willoughby. Hugh L 202

Wilson Aerial Highway 200

Winch for kite balloons 159

Wind channel experiments 275

Winding drum igi

Windlass 16I

Windlass wagon gi

Wing construction 253

Wing section 259

Winter gloves for aviators 191

Winter. Lieut. .John C 204

Wire gauze strainer 250

Wireless 75, 76, 77, 121, 138

aerials ... 142

aero transmitter 150

apparatus. Breguet 148

communication 139

control of artillery fire 142. 149

Culver .".et 154

equipment 138

observer 147

helmet 138

installation 148

receiving apparatus 152

receiving station 151

receiving trucks 144

sets for U. S. Gov 153

signaling 147

speed of sending 141

station, German .... 151

transmission 141, 142

transmission sets 246

trucks 145

units 150

Washington set 153

Wire telephone 140

Wise Wood. Henry A 202, 217. 238

WittemannLewis Co 244. 291

Wood, Brig. Gen. J'red. W 210

Woodhouse, Henry 201, 217, 234, 237

Woods bulls eye 158

Wright 222

Wright aeroplane 204, 207, 226 236

Wright. Captain Frank W 211

Wright-Martin Co 237, 291-292

Wright. Orville

. . . .202. 204, 205, 222, 224, 225. 226

Wright, Rev. Milton 225

Wright. Wilbur 221. 225

Young. Brig.-Gen. L. W 211

Young, William Wallace 202

Zahm, Francis A 202

Zeebrugge 7

Zeppelins 20. 126, 134, 135. 137. 143. 157. 240

bomb 37

bomb dropping mechanism 22

duly 127. 133

raids 24, 125

incendiary Ijomb 34

over Berlin 156

radio 154

(See Textbook of Naval Aeronautics and
D'Orcy's Airship manual.)

wireless 138

wireless stations 152

wreck 110

Zone call system 122

^iAiIi2£i^(i

14 DAY USE

RETURN TO DESK FROM WHICH BORROWED

LOAN DEPT.

This book is due on the last date stamped below, or

on the date to which renewed.

Renewed books ate subject to immediate recall.

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